PopUp Not showing on Mobile

This is the website: http://florencehc.com/ebindersuite-trialsites/

You must click a button to trigger the popup.

When viewing on mobile, the popup is not present. The popup background still appears, but it looks like it's adding CSS declarations of .popup { display:none;} for screens under 800px. I have tried editing this with custom CSS (with !important), but it's overwritten by what I'm assuming is JS.

How can I resolve this issue quickly?