Update app.py

app.py

@@ -60,7 +60,7 @@ def view_model(selected_models):
     return netron_html if netron_html else "<p>No valid models selected for visualization.</p>"
 
 custom_css = """
-#run_button {
+.run_button {
     background-color: purple !important;
     color: white !important;
     width: 120px !important;