Here is a problem which can be found on some other sites using the theme, too.
http://www.anwalt.center
You can't see the menu's writing on mobile view (It's not grey, it isn't there at all). This can be observed on any actual smartphone, but also in the administration area while testing the settings: Desktop is okay, tablet is also okay: But mobile: No text in the upper menu!
I tried all kinds of different settings too, it doesn't change.
This issue is quite important, since customers might have a bad experience right on their first step looking up the site.