Been trying to get this right now for a few days to no avail.
I want the header area to be transparent so, when I select “Place content behind header (sliders etc..): it does that but when it goes to mobile view the content gets all smashed up. The nav menu hasn’t acted right yet either.
Perhaps try adding some top padding to your top Beaver Builder section. It will push the content down so the header doesn’t sit right on top of everything.