Thank you for this. While searching I also found `browser.uidensity`. Setting it to 1 makes the whole UI more compact, which gives some more vertical pixels for the website window.
Wow, browser.proton.enabled and browser.uidensity gives me 1 more pixel than Safari. This is awesome.
Thanks for suggesting setting browser.uidensity to 1, it actually makes bars a lot more compact!
This also fixes Firefox not using the Windows 10 accent color in the titlebar[1], thanks!