fix: increase tab contrast on light theme

app.py

@@ -180,7 +180,7 @@ custom_css = """
     --surface-2: #f1f5f9;
     --border: #e2e8f0;
     --text: #0f172a;
-    --muted: #64748b;
+    --muted: #1f2937; /* darker for readability */
     --accent: #4f46e5;
     --accent-2: #6366f1;
 }
@@ -343,13 +343,17 @@ ul.options, .gr-dropdown-options {
     border-color: #94a3b8 !important;
 }
 
+/* Tabs */
 /* Tabs */
 .tabs button {
-    color: var(--muted) !important;
+    color: #0f172a !important; /* dark text for readability */
+    font-weight: 600 !important;
 }
 .tabs button.selected {
-    color: var(--accent) !important;
-    border-bottom-color: var(--accent) !important;
+    color: #ffffff !important;
+    background: var(--accent) !important;
+    border-radius: 6px !important;
+    padding: 4px 10px !important;
 }
 
 /* Radio buttons */