Steps to reproduce:
Open orion in full screen
From view select Always show toolbar in full screen
(The page then moves to the top and url and tabs are hidden)
Change the tabs via keyboard or trackpad and the new tab page starts a bit lower
Expected behavior:
When changing tabs the page shouldn't come down, as if the page is expecting the toolbar and tabs to be there
I tried the same feature in safari and it works perfectly over there.
0.99.122, M1 MacBook Air
Image/Video:

After changing tabs and going back to same tab this happens( look at the top)
