Thanks for your response, sorry I missed it, I guess I forgot to turn on the notifications. Meanwhile I found another solution though 🙂
I was using Top Bar for another purpose, above the Navigation Bar. So I wanted to use the Header Widget Area below the Navigation Bar. And I wanted to be able to hide it on mobile or desktop with an additional css.
Then I discovered the abilities of Elements and Hooks 🙂 I was a bit confused about them in the beginning, but apparently they are pretty simple to use and have a lot of customisation options.
I made some hooks by adding <div class="hide-on-desktop">content</div> and added them above content. Problem solved 🙂