Bottom positioned NavBar appearing under content

Design help General
1

I have positioned my navbar at the bottom of the page. This works well in Desktop but in Tablet and Mobile mode the menu content seems to be appearing under the page content.

I have tried setting the z-index but that didn’t help. Any thoughts?

Thanks

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

2

Sorry to bump this back up but I am still stuck on this one