Modal on Mobile

Hi,
I absolutely love your plugin and will have no problem going pro once I get it right.
The link above shows the results of a Popup on three different devices.
While the desktop and to a degree, the Ipad are satisfactory, the mobile is a disaster as you will see.
How can I size the Modal for different devices?

Under settings for the plugin, all I can find is:

Note : If you are facing any error related Polyfill JS eg : Uncaught Error: only one instance of babel-polyfill is allowed, than select above option to hide plugin polyfill js or inluclude polyfill js in header so no conflict arise with default js of WordPress. You are getting this error because of there are two version of polyfill.js loading in your website.

which I just don’t understand.

Your comments would be very much appreciated as I don’t want to move away from your plugin.

BJBarker

The page I need help with: [log in to see the link]