Menu and search doesn’t work on mobile

Hello,

When I try to either do a search or click on the menu on the start page on my site a transparent grey layer is appearing over the whole page. It is not possible to click.

I have tested in several browsers.
Cleared cashe.
Tested on several devices.
Same problem on all.

I have deactivated ALL plugins.
Still wrong.

I have changed pages as start page.
Still wrong.

Not I hope someone has any more solutions!
Thank you in advance.

The page I need help with: [log in to see the link]