slick-fox VS firefox-i3wm-theme

I personally use the Slick-Fox userChrome with some tweaks to save on space and fix some aspects I dislike, might help you ? There's also Firefox Color if you need a color theme that fits your color scheme.

It would probably be best if you just shared your whole userChrome.css file. If I try the style sheet from the repository that is mentioned in your link - this one - the result doesn't really look like in your screenshot.

There kinda is, but not like that. slick-fox seems to add a 6px top margin for tabs here - make that 0 or 0px and it should remove the space.

Here is the GitHub Repo: https://github.com/etesam913/slick-fox

get myself https://github.com/Etesam913/slick-fox to hide firefox thick url bar

Searchbar one works well. However, urlbar-search-mode-indicator isn't working for me, for some reason. I'm on v86 (Dev Edition), and using Slickfox userchrome: https://github.com/Etesam913/slick-fox/blob/master/userChrome.css

Just yesterday I was looking into Slick-fox, but I ended up dropping it because it strayed away too much from Firefox's default look. Your theme is exactly what I was looking for. Thank you!

i believe i got the initial code from here: https://github.com/Etesam913/slick-fox/blob/master/userChrome.css

you can accomplish this with edits to userChrome.css. for instance, this i3-inspired theme new windows with only 1 tab have no chrome (no tab bar, no address bar [it auto-hides] etc). the theme itself might not be to your tastes, but you can tweak it.

another one(main branch) have tab button

A similar project I found was firefox-i3wm-theme which was posted several times here but it is currently unmaintained. Minima works really well and it's very easy to customize!

All credit goes to aadilayub who created the original config. I only tweaked it to better suit my needs and added some little detail here and there. It's a mostly keyboard oriented setup.