Update app.css

app.css

@@ -1,17 +1,52 @@
 /* app.css */
 
+/* Define CSS variables for light and dark themes */
+:root {
+    /* Light Theme Variables */
+    --background-color: #ffffff;
+    --text-color: #000000;
+    --card-border-color: #4CAF50; /* Green for active links */
+    --dead-link-color: #D32F2F;   /* Red for dead links */
+    --button-background: #4CAF50;
+    --button-hover-background: #45a049;
+    --file-upload-border: #4CAF50;
+    --file-upload-hover-background: #f1f1f1;
+    --file-upload-hover-color: #45a049;
+    --link-color: #2980B9;
+    --link-hover-color: #1F618D;
+    --output-background: #f0f0f0;
+}
+
+@media (prefers-color-scheme: dark) {
+    :root {
+        /* Dark Theme Variables */
+        --background-color: #121212;
+        --text-color: #ffffff;
+        --card-border-color: #4CAF50;
+        --dead-link-color: #FF6B6B;
+        --button-background: #4CAF50;
+        --button-hover-background: #45a049;
+        --file-upload-border: #4CAF50;
+        --file-upload-hover-background: #1f1f1f;
+        --file-upload-hover-color: #45a049;
+        --link-color: #6FB1FC;
+        --link-hover-color: #5A9BD3;
+        --output-background: #1f1f1f;
+    }
+}
+
 /* General Styling */
 body {
+    background-color: var(--background-color);
+    color: var(--text-color);
     font-family: Arial, Helvetica, sans-serif;
-    background-color: #f9f9f9; /* Light background for the entire app */
-    color: #333333; /* Dark text for readability */
     margin: 0;
     padding: 0;
 }
 
 /* Header Styling */
 h1, h2, h3, h4, h5, h6 {
-    color: #2C3E50; /* Dark blue-gray for headings */
+    color: var(--text-color);
 }
 
 /* Card Styling */
@@ -21,16 +56,28 @@ h1, h2, h3, h4, h5, h6 {
     padding: 15px;
     margin: 10px;
     border-radius: 8px;
-    background-color: #ffffff; /* White background for cards */
+    background-color: var(--background-color);
+    border: 2px solid var(--card-border-color);
 }
 
 .card:hover {
     box-shadow: 0 8px 16px 0 rgba(0,0,0,0.2);
 }
 
+/* Dead Link Styling */
+.dead-link {
+    border-color: var(--dead-link-color) !important;
+    color: var(--dead-link-color) !important;
+}
+
+/* Active Link Styling */
+.active-link {
+    color: var(--text-color) !important;
+}
+
 /* Button Styling */
 button {
-    background-color: #4CAF50; /* Green background for buttons */
+    background-color: var(--button-background);
     border: none;
     color: white;
     padding: 10px 20px;
@@ -45,23 +92,23 @@ button {
 }
 
 button:hover {
-    background-color: #45a049; /* Darker green on hover */
+    background-color: var(--button-hover-background);
 }
 
 /* File Upload Styling */
 input[type="file"] {
-    border: 2px dashed #4CAF50;
+    border: 2px dashed var(--file-upload-border);
     border-radius: 5px;
     padding: 20px;
     text-align: center;
-    color: #4CAF50;
+    color: var(--file-upload-border);
     cursor: pointer;
     transition: background-color 0.3s ease, color 0.3s ease;
 }
 
 input[type="file"]:hover {
-    background-color: #f1f1f1;
-    color: #45a049;
+    background-color: var(--file-upload-hover-background);
+    color: var(--file-upload-hover-color);
 }
 
 /* Dropdown Styling */
@@ -73,6 +120,8 @@ select, .gr-dropdown {
     width: 100%;
     box-sizing: border-box;
     margin-bottom: 10px;
+    background-color: var(--background-color);
+    color: var(--text-color);
 }
 
 /* Checkbox Group Styling */
@@ -97,17 +146,19 @@ textarea, input[type="text"], input[type="number"], input[type="email"], input[t
     border-radius: 4px;
     resize: vertical;
     font-size: 14px;
+    background-color: var(--background-color);
+    color: var(--text-color);
 }
 
 /* Link Styling */
 a {
-    color: #2980B9; /* Blue color for links */
+    color: var(--link-color);
     text-decoration: none;
 }
 
 a:hover {
     text-decoration: underline;
-    color: #1F618D;
+    color: var(--link-hover-color);
 }
 
 /* Markdown Styling */
@@ -117,9 +168,9 @@ a:hover {
 
 /* Output Textbox Styling */
 .gr-output .gr-textbox {
-    background-color: #f0f0f0; /* Light gray background for outputs */
+    background-color: var(--output-background);
     border: 1px solid #ccc;
-    color: #333333;
+    color: var(--text-color);
 }
 
 /* Export Button Styling */