Mobile Menu hides behind content; but only on external host

Hey all,

I’m helping my parents with a website, and the mobile version of the site has a hamburger menu that slides out. It displays fine on Webflow, but once I export it over to their current host, it hides behind the content. I’ve played with Z-index with no luck, and I’m new to all this so I can’t think of any other solution. Does anyone know what might be happening?

My read only is here: https://preview.webflow.com/preview/favron-heating?utm_medium=preview_link&utm_source=designer&utm_content=favron-heating&preview=24e9bb04f11593e3e0cb5e2e5892c5a7&workflow=preview

And this is the current live version: https://www.favronheating.ca/

Thank you!