WackyToaster Thank you for your quick and very detailed answer :)
An iFrame is not possible. I depend on the environment in which the game is to be shown afterwards. The navigation bar is placed on the game as an overlay by this environment, so I don't think an extra layer makes sense, correct? If the navigation were in-game, then yes. But only space should be created and the UI elements should be pushed further down (or to the right) in order to avoid the overlap mentioned.
I have now created a sprite "Spacer" (1x1) and positioned it in the top left corner via "Anchor" (thanks for the confirmation). In theory it now behaves as it should, but I still have problems with the size. Full width and height works now, but how do I ensure a constant height/width of 100 pixels?
If I simply use "Set size" with the value 100, then the value changes proportionally to the window size:
If I make the window smaller, this value also becomes smaller. How can I make 100px fixed?
Thanks :)