This PR adds color code for button

Add the feature of standard color code for the Run button. It helps the users to understand how the space works.

Click on _Merge_ to add this feature.

app.py

@@ -337,7 +337,7 @@ with gr.Blocks(css=css) as demo:
                 container=False,
             )
 
-            run_button = gr.Button("Run", scale=0)
+            run_button = gr.Button("Run", scale=0, variant="primary")
 
         result = gr.Image(label="Result", show_label=False)