show spinner while demo is loading

website/demo.py

@@ -52,8 +52,9 @@ def demo(f: Callable) -> Callable:
                 .classes('absolute right-2 top-10 opacity-10 hover:opacity-80 cursor-pointer') \
                 .on('click', copy_code, [])
         with browser_window(title=getattr(f, 'tab', None),
-                            classes='w-full max-w-[44rem] min-[1500px]:max-w-[20rem] min-h-[10rem] browser-window'):
-            intersection_observer(on_intersection=f)
+                            classes='w-full max-w-[44rem] min-[1500px]:max-w-[20rem] min-h-[10rem] browser-window') as window:
+            ui.spinner(size='lg').props('thickness=2')
+            intersection_observer(on_intersection=lambda: (window.clear(), f()))
     return f