Z Index Overlay CMSs

Hi there,
i’ve a problem with Z-Index items.

How you can see in my loom i’ve a overlay problem with z-index overlay in page “about-us”.

In Normal screens it’s work correctly, BUT in big screens it doesn’t work, BUT i don’t touch any class…
Thanks for your help

Here is my site Read-Only: [LINK][1]
([how to share your site Read-Only link][2])