No longer have vertical lines between unused tabs


Says that I can’t have lines separating my unused tabs anymore. This is SO annoying. Can anyone help me get borders between my unused tabs?

Also, WHY ARE YOU DOING THIS Mozilla? Now I have to stop EVERYTHING that I am doing and research how I can make your browser work the way I want it to. Why do you always assume that you know what is best for me?

The Firefox Universe is extremely vast, and trying to Google “lines between my unused tabs” is getting me nowhere. I don’t know how to develop themes. I don’t code. I just want the browser to look like it did last week. Is it really so much to ask?

Every. Single. Time. I update Firefox, I regret it!!!


I don’t believe you’ll get any answer from the FF developers but what you can try is to disable the whole Proton UI refresh-mess:

  1. Open about:config
  2. Type “proton” in the search bar
  3. Look for the option browser.proton.enabled
  4. Double-click it to set it to false!

And that should instantly restore sanity to the browser UI – it did for me, and I hope it will also do for you!


Thank you, this was suggested on another thread I started, and it works for now. At some point, I’m sure Mozilla will decide that I shouldn’t be able to make that customization anymore.

Interesting/prophetic article about Mozilla’s missteps with Firefox:

1 Like

Thanks for the tip. The invisible tabs bothered me as well.

Indeed that does seem a prophetic article and I too wonder for how much longer we are allowed to enjoy a usable UI on Firefox.

I’m beginning to dust off Vivaldi. :frowning:

1 Like

… tabs restyled …

More at

Thanks for giving the tip about Vivaldi! Didn’t know about that browser. I have installed and love the resemblance to Opera as it was up until version 12. That used to be my favourite browser before that huge overhaul when it was “chromatized” and lost all those unique features it used to have which made me give up on Opera (just as I might give up on FF if this proton-UI nonsense becomes permanent). I was even able to install Vivaldi on my work laptop as it unusually could be installed without having administrative privileges :smiley:

1 Like

Sadly, disabling proton in about:config no longer works (if it ever did on Mac). Please Mozilla, roll this change back or provide a way to customize it. Changes like this are why I wait months between Firefox updates.

Isn’t that lovely? We figure out a way to bring back a feature that we like and need, and Mozilla comes along and says… “Oh you still want that? NO YOU CAN’T HAVE IT!!! WE DON’T CARE HOW MUCH IT HELPS YOU, YOU CAN’T, YOU CAN’T, YOU CAN’T, AND STOP TRYING!!”

That was only for Firefox 89-90. The is no built-in feature to add separators between background tabs. There also is no built-in feature for customizing tab appearance.

If you are interested in an unofficial, community-supported workaround, we have the option of creating a userChrome.css file. I have a website about that, and also a rule generator to restyle the tab bar. If you want to know specific steps, let me know.