RevertFFToolbar

A userChrome.css script to revert the changes to the toolbar in Firefox 110.

What did Mozilla do this time?

The toolbar received an update on December 22nd which made it look, in my opinion, much worse:

The dark system theme was made brighter and now does not fit with the dark theme of any OS.
The text on the selected tab was made bold.

To communicate the difference more clearly, here's a before and after: (I'm using WaveFox, but it looks the same on the normal one too)

How do I use this?

In about:config, set toolkit.legacyUserProfileCustomizations.stylesheets to true if you have not already.
Go to your Firefox profile folder. For convenience, use about:profiles.
Create a folder named chrome if it's not there already.
Drop the userChrome.css file right in.
Restart Firefox.