Desktop Menu not scaling properly

I have a website in development migration2.smartopensoft.net/ and the Menu does not scale properly when scaling the visible screen smaller to a size of a tablet.
This happens with large menus. It cuts it off to the right and puts it below the main menu line but it only appears on hover.

Is there a way to manipulate template to show the mobile menu earlier e.g. 1280px width?

Search the forum > breakpoints
It was very often talk about this...