Update app.py

app.py

@@ -2336,15 +2336,22 @@ SELECTION_JS = """
         document.body.classList.toggle('dark', dark);
         const container = document.querySelector('.gradio-container');
         if (container) container.classList.toggle('dark', dark);
-        // Sync emoji and checkbox — retry until element is available
+    
         function syncUI() {
             const el = document.getElementById('theme-emoji');
             const cb = document.getElementById('dark-toggle-btn');
             if (el) el.textContent = dark ? '☀️' : '🌙';
             if (cb) cb.checked = dark;
-            if (!el || !cb) requestAnimationFrame(syncUI);
+            if (el && cb) return true;
+            return false;
+        }
+    
+        if (!syncUI()) {
+            const observer = new MutationObserver(() => {
+                if (syncUI()) observer.disconnect();
+            });
+            observer.observe(document.body, { childList: true, subtree: true });
         }
-        syncUI();
     }
     function toggleDark() {
         const url = new URL(window.location);