I noticed that many people have trouble with the website content jumping down when moving the cursor to the top corner.
You often have navigation items close to the upper part of the website, so many people bump accidentally with their mouse cursor in the top border of the screen, triggering the Browser UI popping up and moving everything.
Maybe a fixed position with some slide-transition could make the whole experience smoother.
(I'm using Firefox on Debian Linux and don't know if Firefox behaves everywhere the same way)
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