click to call attaching to body not header

I have a site using Parallax scrolling. I created a click to call button which shows fine, but it is attached to the body layer, not above the sticky header with the navigation control. How do I fix this? Kinda hard to explain, but you can see what I mean by going to https://www.cmhtechnology.com on a mobile device, and try scrolling down.

https://www.ads-software.com/plugins/insite-for-wp-personalization-made-easy/