diff --git a/public/404.html b/public/404.html
index e9e842c..a8bd431 100644
--- a/public/404.html
+++ b/public/404.html
@@ -11,7 +11,48 @@
       <p>Sorry, we couldn't find that! Check out the <a href="./">home page</a>?</p>
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
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     </div>
diff --git a/public/arrays b/public/arrays
index b333813..63c0bb1 100644
--- a/public/arrays
+++ b/public/arrays
@@ -188,7 +188,48 @@ when printed with <code>fmt.Println</code>.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
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     </div>
diff --git a/public/atomic-counters b/public/atomic-counters
index 6548101..34a3178 100644
--- a/public/atomic-counters
+++ b/public/atomic-counters
@@ -226,7 +226,48 @@ state.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
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     </div>
diff --git a/public/base64-encoding b/public/base64-encoding
index c2db003..01e8c7f 100644
--- a/public/base64-encoding
+++ b/public/base64-encoding
@@ -182,7 +182,48 @@ but they both decode to the original string as desired.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
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     </div>
diff --git a/public/channel-buffering b/public/channel-buffering
index 3975022..9521b7c 100644
--- a/public/channel-buffering
+++ b/public/channel-buffering
@@ -144,7 +144,48 @@ concurrent receive.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/channel-directions b/public/channel-directions
index 5695a28..d0ec8e0 100644
--- a/public/channel-directions
+++ b/public/channel-directions
@@ -136,7 +136,48 @@ receive on this channel.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/channel-synchronization b/public/channel-synchronization
index 9061590..38f4711 100644
--- a/public/channel-synchronization
+++ b/public/channel-synchronization
@@ -175,7 +175,48 @@ started.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/channels b/public/channels
index 3b161a7..63eb7d3 100644
--- a/public/channels
+++ b/public/channels
@@ -160,7 +160,48 @@ message without having to use any other synchronization.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/closing-channels b/public/closing-channels
index d1fad4f..23c99cd 100644
--- a/public/closing-channels
+++ b/public/closing-channels
@@ -186,7 +186,48 @@ example: <code>range</code> over channels.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/closures b/public/closures
index 8b8edd0..ee50d20 100644
--- a/public/closures
+++ b/public/closures
@@ -181,7 +181,48 @@ recursion.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/command-line-arguments b/public/command-line-arguments
index b0d5322..2ecfbc0 100644
--- a/public/command-line-arguments
+++ b/public/command-line-arguments
@@ -161,7 +161,48 @@ with flags.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/command-line-flags b/public/command-line-flags
index 92e2f2e..b161e8f 100644
--- a/public/command-line-flags
+++ b/public/command-line-flags
@@ -297,7 +297,48 @@ and show the help text again.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/command-line-subcommands b/public/command-line-subcommands
index 9ea0cba..d194859 100644
--- a/public/command-line-subcommands
+++ b/public/command-line-subcommands
@@ -251,7 +251,48 @@ way to parameterize programs.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/constants b/public/constants
index 0188473..419f008 100644
--- a/public/constants
+++ b/public/constants
@@ -174,7 +174,48 @@ assignment or function call. For example, here
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/context b/public/context
index 576162f..7f843a0 100644
--- a/public/context
+++ b/public/context
@@ -196,7 +196,48 @@ cancellation.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/defer b/public/defer
index 2e48c9e..60cbb6d 100644
--- a/public/defer
+++ b/public/defer
@@ -200,7 +200,48 @@ after being written.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/directories b/public/directories
index bef7856..7f055a0 100644
--- a/public/directories
+++ b/public/directories
@@ -338,7 +338,48 @@ recursively by <code>filepath.Walk</code>.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/embed-directive b/public/embed-directive
index 906bece..9a726ba 100644
--- a/public/embed-directive
+++ b/public/embed-directive
@@ -201,7 +201,48 @@ this example can only be run on your local machine.)</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/environment-variables b/public/environment-variables
index f0d0e5e..a951057 100644
--- a/public/environment-variables
+++ b/public/environment-variables
@@ -177,7 +177,48 @@ program picks that value up.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/epoch b/public/epoch
index 890b66e..0f2ef53 100644
--- a/public/epoch
+++ b/public/epoch
@@ -161,7 +161,48 @@ parsing and formatting.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/errors b/public/errors
index 9444171..971665b 100644
--- a/public/errors
+++ b/public/errors
@@ -287,7 +287,48 @@ on the Go blog for more on error handling.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/execing-processes b/public/execing-processes
index 6e9c5a3..4630748 100644
--- a/public/execing-processes
+++ b/public/execing-processes
@@ -195,7 +195,48 @@ processes covers most use cases for <code>fork</code>.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/exit b/public/exit
index 902ba78..8347c3e 100644
--- a/public/exit
+++ b/public/exit
@@ -161,7 +161,48 @@ the status in the terminal.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/file-paths b/public/file-paths
index d129bde..ecab361 100644
--- a/public/file-paths
+++ b/public/file-paths
@@ -240,7 +240,48 @@ be made relative to base.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/for b/public/for
index e5b9674..4f52777 100644
--- a/public/for
+++ b/public/for
@@ -186,7 +186,48 @@ structures.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/functions b/public/functions
index 74e7302..f837c2a 100644
--- a/public/functions
+++ b/public/functions
@@ -183,7 +183,48 @@ multiple return values, which we&rsquo;ll look at next.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/generics b/public/generics
index 721f0f7..f4ad3e1 100644
--- a/public/generics
+++ b/public/generics
@@ -238,7 +238,48 @@ automatically.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/goroutines b/public/goroutines
index 957edc6..76accd7 100644
--- a/public/goroutines
+++ b/public/goroutines
@@ -199,7 +199,48 @@ concurrent Go programs: channels.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/hello-world b/public/hello-world
index 6f28be4..5403f5d 100644
--- a/public/hello-world
+++ b/public/hello-world
@@ -126,7 +126,48 @@ learn more about the language.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/http-client b/public/http-client
index 763290b..5182728 100644
--- a/public/http-client
+++ b/public/http-client
@@ -160,7 +160,48 @@ settings.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/http-server b/public/http-server
index 70cdb54..5aae931 100644
--- a/public/http-server
+++ b/public/http-server
@@ -201,7 +201,48 @@ router we&rsquo;ve just set up.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
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diff --git a/public/if-else b/public/if-else
index ec12be9..d2455b1 100644
--- a/public/if-else
+++ b/public/if-else
@@ -175,7 +175,48 @@ for basic conditions.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
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+          var body = document.getElementsByTagName('body')[0];
+
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+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
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+            activateTheme('light');
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+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
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diff --git a/public/index.html b/public/index.html
index 98549d6..3328a1d 100644
--- a/public/index.html
+++ b/public/index.html
@@ -190,7 +190,48 @@
       </ul>
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
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diff --git a/public/interfaces b/public/interfaces
index 36cef1b..6410da7 100644
--- a/public/interfaces
+++ b/public/interfaces
@@ -227,7 +227,48 @@ these structs as arguments to <code>measure</code>.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
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+
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+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
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+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
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+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
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diff --git a/public/json b/public/json
index f1d7040..c2d3e44 100644
--- a/public/json
+++ b/public/json
@@ -403,7 +403,48 @@ for more.</p>
       
 
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-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
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diff --git a/public/line-filters b/public/line-filters
index 3fcb704..b7d0ab6 100644
--- a/public/line-filters
+++ b/public/line-filters
@@ -194,7 +194,48 @@ lowercase lines.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
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diff --git a/public/maps b/public/maps
index bf99e93..a5b767c 100644
--- a/public/maps
+++ b/public/maps
@@ -224,7 +224,48 @@ printed with <code>fmt.Println</code>.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
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diff --git a/public/methods b/public/methods
index b04b063..0c9828a 100644
--- a/public/methods
+++ b/public/methods
@@ -187,7 +187,48 @@ naming related sets of methods: interfaces.</p>
       
 
     <p class="footer">
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+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
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diff --git a/public/multiple-return-values b/public/multiple-return-values
index 9fbc33d..7c8e48e 100644
--- a/public/multiple-return-values
+++ b/public/multiple-return-values
@@ -157,7 +157,48 @@ feature of Go functions; we&rsquo;ll look at this next.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
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+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
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diff --git a/public/mutexes b/public/mutexes
index 9dc784d..bff492c 100644
--- a/public/mutexes
+++ b/public/mutexes
@@ -241,7 +241,48 @@ management task using only goroutines and channels.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
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diff --git a/public/non-blocking-channel-operations b/public/non-blocking-channel-operations
index 08d4bd6..2a26abd 100644
--- a/public/non-blocking-channel-operations
+++ b/public/non-blocking-channel-operations
@@ -167,7 +167,48 @@ on both <code>messages</code> and <code>signals</code>.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/number-parsing b/public/number-parsing
index af3d1d4..c744839 100644
--- a/public/number-parsing
+++ b/public/number-parsing
@@ -205,7 +205,48 @@ bits.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/panic b/public/panic
index a93770c..9246ddb 100644
--- a/public/panic
+++ b/public/panic
@@ -176,7 +176,48 @@ to use error-indicating return values wherever possible.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/pointers b/public/pointers
index b57507a..4e2458a 100644
--- a/public/pointers
+++ b/public/pointers
@@ -184,7 +184,48 @@ the memory address for that variable.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/random-numbers b/public/random-numbers
index c1571e2..ce784e8 100644
--- a/public/random-numbers
+++ b/public/random-numbers
@@ -226,7 +226,48 @@ that Go can provide.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/range b/public/range
index 5259ac7..4ef6efd 100644
--- a/public/range
+++ b/public/range
@@ -193,7 +193,48 @@ details.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/range-over-channels b/public/range-over-channels
index bc4b71e..5e443c2 100644
--- a/public/range-over-channels
+++ b/public/range-over-channels
@@ -145,7 +145,48 @@ values be received.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/rate-limiting b/public/rate-limiting
index ceb2a71..2824710 100644
--- a/public/rate-limiting
+++ b/public/rate-limiting
@@ -252,7 +252,48 @@ then serve the remaining 2 with ~200ms delays each.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/reading-files b/public/reading-files
index 58fc5bc..80092f1 100644
--- a/public/reading-files
+++ b/public/reading-files
@@ -277,7 +277,48 @@ be scheduled immediately after <code>Open</code>ing with
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/recover b/public/recover
index 903dbf8..55550b5 100644
--- a/public/recover
+++ b/public/recover
@@ -186,7 +186,48 @@ panic and resumes in the deferred closure.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/recursion b/public/recursion
index 413b684..53cb125 100644
--- a/public/recursion
+++ b/public/recursion
@@ -172,7 +172,48 @@ knows which function to call with <code>fib</code> here.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/regular-expressions b/public/regular-expressions
index 9f830f0..100ec68 100644
--- a/public/regular-expressions
+++ b/public/regular-expressions
@@ -334,7 +334,48 @@ the <a href="https://pkg.go.dev/regexp"><code>regexp</code></a> package docs.</p
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/select b/public/select
index 8132666..f52596a 100644
--- a/public/select
+++ b/public/select
@@ -174,7 +174,48 @@ concurrently.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/sha256-hashes b/public/sha256-hashes
index e1e1846..815aeb2 100644
--- a/public/sha256-hashes
+++ b/public/sha256-hashes
@@ -190,7 +190,48 @@ you should carefully research
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/signals b/public/signals
index 42710f2..153fec1 100644
--- a/public/signals
+++ b/public/signals
@@ -204,7 +204,48 @@ causing the program to print <code>interrupt</code> and then exit.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/site.js b/public/site.js
index 752e656..d07d82e 100644
--- a/public/site.js
+++ b/public/site.js
@@ -15,3 +15,45 @@ var clipboard = new Clipboard('.copy', {
         return codeLines.filter(function(cL) { return cL != '' }).join("\n").replace(/\n$/, '');
     }
 });
+
+
+/**
+ * Code for theme switching
+ */
+
+
+// var themeButton = document.getElementById('theme-button');
+// var body = document.getElementsByTagName('body')[0];
+
+
+// function activateDarkTheme(){
+//     body.style.color = "#ffffffeb"
+//     body.style.backgroundColor = "#1a202c"
+//     localStorage.setItem('theme', 'dark')
+// }
+
+// function activateLightTheme(){
+//     body.style.color = "#252519"
+//     body.style.backgroundColor = "white"
+//     localStorage.setItem('theme', 'light')
+// }
+
+// if (localStorage.getItem('theme') === 'light') {
+//     activateLightTheme()
+// } else if (localStorage.getItem('theme') === 'dark'){
+//     activateDarkTheme()
+// }
+
+// themeButton.onclick = function(){
+//     if (localStorage.getItem('theme') === 'dark'){
+//         activateLightTheme()
+//     } else if (localStorage.getItem('theme') === 'light'){
+//         activateDarkTheme()
+//     } else {
+//         if (body.style.color === "white"){
+//             activateDarkTheme()
+//         } else {
+//             activateLightTheme()
+//         }
+//     }
+// }
\ No newline at end of file
diff --git a/public/slices b/public/slices
index 78c327a..492f50d 100644
--- a/public/slices
+++ b/public/slices
@@ -300,7 +300,48 @@ Go&rsquo;s other key builtin data structure: maps.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/sorting b/public/sorting
index e3c3508..bd03bd7 100644
--- a/public/sorting
+++ b/public/sorting
@@ -152,7 +152,48 @@ slices and <code>true</code> as the result of our <code>AreSorted</code> test.</
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/sorting-by-functions b/public/sorting-by-functions
index 1607ffa..e31bf48 100644
--- a/public/sorting-by-functions
+++ b/public/sorting-by-functions
@@ -170,7 +170,48 @@ functions.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/spawning-processes b/public/spawning-processes
index d013fc1..cf9b386 100644
--- a/public/spawning-processes
+++ b/public/spawning-processes
@@ -274,7 +274,48 @@ an error message and non-zero return code.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/stateful-goroutines b/public/stateful-goroutines
index 119f08b..03ca520 100644
--- a/public/stateful-goroutines
+++ b/public/stateful-goroutines
@@ -304,7 +304,48 @@ program.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/string-formatting b/public/string-formatting
index eb6b45b..5d5f647 100644
--- a/public/string-formatting
+++ b/public/string-formatting
@@ -447,7 +447,48 @@ and returns a string without printing it anywhere.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/string-functions b/public/string-functions
index 0b38f93..275ef0b 100644
--- a/public/string-functions
+++ b/public/string-functions
@@ -154,7 +154,48 @@ package docs.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/strings-and-runes b/public/strings-and-runes
index a7fc03e..8276af9 100644
--- a/public/strings-and-runes
+++ b/public/strings-and-runes
@@ -274,7 +274,48 @@ can compare a <code>rune</code> value to a rune literal directly.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/struct-embedding b/public/struct-embedding
index c70b5b9..5126ee9 100644
--- a/public/struct-embedding
+++ b/public/struct-embedding
@@ -238,7 +238,48 @@ we see that a <code>container</code> now implements the
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/structs b/public/structs
index 84de85f..cb51e79 100644
--- a/public/structs
+++ b/public/structs
@@ -257,7 +257,48 @@ pointers are automatically dereferenced.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/switch b/public/switch
index aaab93d..0c20392 100644
--- a/public/switch
+++ b/public/switch
@@ -194,7 +194,48 @@ type corresponding to its clause.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/temporary-files-and-directories b/public/temporary-files-and-directories
index fc173a7..e066b06 100644
--- a/public/temporary-files-and-directories
+++ b/public/temporary-files-and-directories
@@ -230,7 +230,48 @@ prefixing them with our temporary directory.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/testing-and-benchmarking b/public/testing-and-benchmarking
index 176b37f..b03b560 100644
--- a/public/testing-and-benchmarking
+++ b/public/testing-and-benchmarking
@@ -276,7 +276,48 @@ benchmark function names with a regexp.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/text-templates b/public/text-templates
index df0d536..992d05f 100644
--- a/public/text-templates
+++ b/public/text-templates
@@ -265,7 +265,48 @@ the range block <code>{{.}}</code> is set to the current item of the iteration.<
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/tickers b/public/tickers
index 97ca3b5..0ce4a93 100644
--- a/public/tickers
+++ b/public/tickers
@@ -162,7 +162,48 @@ before we stop it.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/time b/public/time
index c8a2d52..938046b 100644
--- a/public/time
+++ b/public/time
@@ -261,7 +261,48 @@ the Unix epoch.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
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+              styleAllTags('td.code.empty', 'background', '#1a202c')
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+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
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+            activateTheme(newTheme);
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+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
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diff --git a/public/time-formatting-parsing b/public/time-formatting-parsing
index 7999890..953db05 100644
--- a/public/time-formatting-parsing
+++ b/public/time-formatting-parsing
@@ -195,7 +195,48 @@ explaining the parsing problem.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
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+
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+          var body = document.getElementsByTagName('body')[0];
+
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+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
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+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
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+            activateTheme('light');
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+
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+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
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+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
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diff --git a/public/timeouts b/public/timeouts
index db72edf..a797d66 100644
--- a/public/timeouts
+++ b/public/timeouts
@@ -173,7 +173,48 @@ out and the second succeeding.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
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     </div>
diff --git a/public/timers b/public/timers
index 2f1f1c9..1592b25 100644
--- a/public/timers
+++ b/public/timers
@@ -176,7 +176,48 @@ a chance to fire.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
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+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
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+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
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diff --git a/public/url-parsing b/public/url-parsing
index 61989e4..1132c4d 100644
--- a/public/url-parsing
+++ b/public/url-parsing
@@ -227,7 +227,48 @@ pieces that we extracted.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
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diff --git a/public/values b/public/values
index 1f04b37..639cd29 100644
--- a/public/values
+++ b/public/values
@@ -143,7 +143,48 @@ basic examples.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
     </p>
 
     </div>
diff --git a/public/variables b/public/variables
index 11c6fee..52edf3a 100644
--- a/public/variables
+++ b/public/variables
@@ -175,7 +175,48 @@ This syntax is only available inside functions.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
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+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
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diff --git a/public/variadic-functions b/public/variadic-functions
index 8b86793..6c332a3 100644
--- a/public/variadic-functions
+++ b/public/variadic-functions
@@ -177,7 +177,48 @@ to form closures, which we&rsquo;ll look at next.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
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+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
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diff --git a/public/waitgroups b/public/waitgroups
index 38870e6..8969237 100644
--- a/public/waitgroups
+++ b/public/waitgroups
@@ -243,7 +243,48 @@ is likely to be different for each invocation.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
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+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
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diff --git a/public/worker-pools b/public/worker-pools
index 601a84f..86874a4 100644
--- a/public/worker-pools
+++ b/public/worker-pools
@@ -214,7 +214,48 @@ there are 3 workers operating concurrently.</p>
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
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+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
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diff --git a/public/writing-files b/public/writing-files
index c9864b0..ddd3d96 100644
--- a/public/writing-files
+++ b/public/writing-files
@@ -277,7 +277,48 @@ we&rsquo;ve just seen to the <code>stdin</code> and <code>stdout</code> streams.
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
+
+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
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diff --git a/public/xml b/public/xml
index 26752fe..271e159 100644
--- a/public/xml
+++ b/public/xml
@@ -268,7 +268,48 @@ to nest all <code>plant</code>s under <code>&lt;parent&gt;&lt;child&gt;...</code
       
 
     <p class="footer">
-      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
+      <script>
+        window.onload = function() {
+          function styleAllTags(tag, style, value){
+            document.querySelectorAll(tag).forEach((tag) => {
+              tag.style[style] = value
+            })
+          }
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+          var themeButton = document.getElementById('theme-button');
+          var body = document.getElementsByTagName('body')[0];
+
+          function activateTheme(theme) {
+            if (theme === 'dark') {
+              body.style.color = "#ffffffeb";
+              body.style.backgroundColor = "#1a202c";
+              styleAllTags('a', 'color', '#ffffffeb')
+              styleAllTags('td.code', 'background', '#333333')
+              styleAllTags('td.code.empty', 'background', '#1a202c')
+            } else {
+              body.style.color = "#252519";
+              body.style.backgroundColor = "white";
+              styleAllTags('a', 'color', '#252519')
+              styleAllTags('td.code', 'background', '#f0f0f0')
+              styleAllTags('td.code.empty', 'background', 'white')
+            }
+            localStorage.setItem('theme', theme);
+          }
+
+          var currentTheme = localStorage.getItem('theme');
+          if (currentTheme === 'light' || currentTheme === 'dark') {
+            activateTheme(currentTheme);
+          } else {
+            activateTheme('light');
+          }
+
+          themeButton.onclick = function() {
+            var newTheme = localStorage.getItem('theme') === 'dark' ? 'light' : 'dark';
+            activateTheme(newTheme);
+          }
+        }
+      </script>
+      by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
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