Perhaps setting the UI density to “compact” will help? I like minimal UI, but Chrome’s feels a bit too minimal. I think Firefox on compact is a perfect balance.

For everyone looking: Hamburger menu -> Customise -> at the bottom Density -> Compact.

Thanks!

I also completely overlooked that setting, even though I had changed many others away from the defaults. Thanks for pointing it out!

Thank you very much, learned something new. I removed the Title bar too, makes ff more compact than chromium.

I've got an instance of both Chrome and Firefox open on MacOS right now, and the UI's use exactly the same amount of space. The navigation bar on Firefox is a little thicker than Chrome, but it's made up for with a slightly thinner tab bar (since FF tabs don't have the blank space above to make them look like physical folder tabs).

Not sure if this holds in Linux or Windows.

EDIT: In fact I just noticed that Chrome was outdated. After upgrading it to the latest build, it uses more screen real estate for the UI than FF Quantum's latest build. The difference is even more pronounced if you have bookbar bars turned on.

If you haven't seen it, you can put dev tools in its own window.