If you want the widget to appear only on mobile devices, follow these steps:
Go to Widget > Edit Widget Settings.
Open the Calls tab.
Enable Show widget on mobile devices.
Navigate to Widget's view > Custom styles.
Paste the following CSS code to adjust the widget button size on mobile:
@media only screen and (max-width: 767px) {
#callpage .cp-widget-button {
width: 42px!important;
height: 70px!important;
}
After saving, the widget will be visible only on screens up to 767px wide, which typically covers smartphones and small tablets.