Update app.py

app.py

@@ -267,7 +267,16 @@ with block:
         with gr.Column():
             gallery = gr.Gallery(label="Generated images", show_label=False, height="auto")
 #            gallery = gr.Gallery(label="Generated images", show_label=False).style(height="auto")
-
+    dropdown.change(None, dropdown, None, _js=js)
+    toggle_dark.click(
+        None,
+        _js="""
+        () => {
+            document.body.classList.toggle('dark');
+            document.querySelector('gradio-app').style.backgroundColor = 'var(--color-background-primary)'
+        }
+        """,
+    )
     run_button.click(fn=canny, inputs=[input_image, resolution, low_threshold, high_threshold], outputs=[gallery])
 
     gr.Markdown("<hr>")