diff --git a/farsi_transcriber/ui/main_window.py b/farsi_transcriber/ui/main_window.py
index 657e866..3fbd371 100644
--- a/farsi_transcriber/ui/main_window.py
+++ b/farsi_transcriber/ui/main_window.py
@@ -24,6 +24,7 @@ from PyQt6.QtGui import QFont
 
 from farsi_transcriber.models.whisper_transcriber import FarsiTranscriber
 from farsi_transcriber.utils.export import TranscriptionExporter
+from farsi_transcriber.ui.styles import get_stylesheet, get_color
 
 
 class TranscriptionWorker(QThread):
@@ -85,6 +86,8 @@ class MainWindow(QMainWindow):
         self.selected_file = None
         self.transcription_worker = None
         self.last_result = None
+        # Apply stylesheet
+        self.setStyleSheet(get_stylesheet())
         self.init_ui()
 
     def init_ui(self):
@@ -121,10 +124,6 @@ class MainWindow(QMainWindow):
 
         # Transcribe button
         self.transcribe_button = QPushButton("Transcribe")
-        self.transcribe_button.setStyleSheet(
-            "background-color: #4CAF50; color: white; font-weight: bold; "
-            "padding: 8px; border-radius: 4px; font-size: 12pt;"
-        )
         self.transcribe_button.clicked.connect(self.on_transcribe)
         self.transcribe_button.setEnabled(False)
         main_layout.addWidget(self.transcribe_button)
@@ -152,9 +151,9 @@ class MainWindow(QMainWindow):
         self.results_text.setPlaceholderText(
             "Transcription results will appear here..."
         )
-        self.results_text.setStyleSheet(
-            "border: 1px solid #ccc; border-radius: 4px; font-family: 'Courier New';"
-        )
+        # Set monospace font for results
+        mono_font = QFont("Courier New", 10)
+        self.results_text.setFont(mono_font)
         main_layout.addWidget(self.results_text)
 
         # Buttons layout (Export, Clear)
diff --git a/farsi_transcriber/ui/styles.py b/farsi_transcriber/ui/styles.py
new file mode 100644
index 0000000..e60979a
--- /dev/null
+++ b/farsi_transcriber/ui/styles.py
@@ -0,0 +1,107 @@
+"""
+Application styling and theming
+
+Provides stylesheet and styling utilities for the Farsi Transcriber app.
+"""
+
+# Modern, professional dark-themed stylesheet
+MAIN_STYLESHEET = """
+QMainWindow {
+    background-color: #f5f5f5;
+}
+
+QLabel {
+    color: #333333;
+}
+
+QLineEdit, QTextEdit {
+    background-color: #ffffff;
+    color: #333333;
+    border: 1px solid #d0d0d0;
+    border-radius: 4px;
+    padding: 5px;
+    font-size: 11pt;
+}
+
+QLineEdit:focus, QTextEdit:focus {
+    border: 2px solid #4CAF50;
+    background-color: #fafafa;
+}
+
+QPushButton {
+    background-color: #4CAF50;
+    color: white;
+    border: none;
+    border-radius: 4px;
+    padding: 8px 16px;
+    font-weight: bold;
+    font-size: 11pt;
+    min-height: 32px;
+}
+
+QPushButton:hover {
+    background-color: #45a049;
+}
+
+QPushButton:pressed {
+    background-color: #3d8b40;
+}
+
+QPushButton:disabled {
+    background-color: #cccccc;
+    color: #999999;
+}
+
+QProgressBar {
+    border: 1px solid #d0d0d0;
+    border-radius: 4px;
+    text-align: center;
+    background-color: #ffffff;
+    height: 20px;
+}
+
+QProgressBar::chunk {
+    background-color: #4CAF50;
+    border-radius: 3px;
+}
+
+QMessageBox QLabel {
+    color: #333333;
+}
+
+QMessageBox QPushButton {
+    min-width: 60px;
+}
+"""
+
+# Color palette
+COLORS = {
+    "primary": "#4CAF50",
+    "primary_hover": "#45a049",
+    "primary_active": "#3d8b40",
+    "background": "#f5f5f5",
+    "text": "#333333",
+    "text_secondary": "#666666",
+    "border": "#d0d0d0",
+    "success": "#4CAF50",
+    "error": "#f44336",
+    "warning": "#ff9800",
+    "info": "#2196F3",
+}
+
+# Font settings
+FONTS = {
+    "default_size": 11,
+    "title_size": 16,
+    "mono_family": "Courier New",
+}
+
+
+def get_stylesheet() -> str:
+    """Get the main stylesheet for the application"""
+    return MAIN_STYLESHEET
+
+
+def get_color(color_name: str) -> str:
+    """Get a color from the palette"""
+    return COLORS.get(color_name, "#000000")