[semiotic1]

https://github.com/black7375/Firefox-UI-Fix fixes most of the frustrating bits of Proton you describe.

It's arguably not the same as a sensible out-of-the box design, but far better than sticking to old versions just because of the UI.

[arp242]

I didn't care much for these entire UI revamps as I felt they were far too complex, so I wrote a much simpler one: https://github.com/arp242/MartinFox

2174 lines of CSS vs. 53 lines :-)

I don't overly care how every pixel looks or what the icon is and such; I just want my tabs to have some contrast.