Nothing.

[crambaud]

Nothing.

[andreasgrafen]

I've just tried it on my machine and while it seems like Waterfall needs some updates it generally is working. The user.js file just reads in settings but the file isn't necessary to make userChrome themes work.
Have you tried another theme to further track down the issue?

[Animationss]

Have you tried another theme to further track down the issue?

Yea I used Firefox Orchis theme And it worked perfectly, I also tried cascade But it didn't work. The only thing I noticed was different was that Orchis used imports in the userChrome file with a extra folder in chrome. But idk if that should make a difference.

[andreasgrafen]

Sorry for the delayed answer.
That's really weird behaviour. I've been trying to figure out what might cause this, but I haven't been ablte to reproduce this in any way. I can get both Waterfall and Cascade to work reliably.. So I can't give any more ideas than to recheck if all the settings are set correctly and everything is properly put into the chrome folder in your FF profile. o:

[Animationss]

That's really weird behaviour.

Yea, I got a css to work and I ended up editing it to my liking, So this css is no longer needed but it would be nice to have cause it looks better then mine. I've provided the chrome folder copy pasted in this github link. Maybe this could help u pin down the issue.

Edit: I should have said this in the first post but im using firefox version 101.0.1 on Linux Mint 20.3 Una