Trouble when viewing site on mobile

Hello!

I’m using the 907 theme, and I’m basically all done with my site, but when I view it on my phone, the first page and the menu bar is kind of overlapping. The ‘home’ page (first page) seems to start under the menu bar!
I’ve changed the height and padding etc. of both the logo and the menu bar manually in the CSS and in my header.php, so I’m guessing that’s where the trouble lays? In terms of the responsiveness not working fully on the phone?

This is my site:
https://vaktmestertjenesten.vaktmestertjenesten.no/

Appreciate any help with this, going absolutely crazy. Thank you!!