Colorlicious

[mikeysc]

If you just want to change/tweak the default theme color, you might want to try Colorlicious. It is pretty good with light to medium colored toolbars. With dark colored toolbars, text on the active tab won't be as visible (never did reverse in my tests). But it's definitely easier and quicker than editing css code. It's quick to change among your preset color combinations once you save them. It seems like it has no affect on performance (I suspect it's light on resources but difficult to quantify). If there is a better option for something like this in PM 24+, I'd like to know. (Not stylish, or anything like that, for me.)

https://addons.mozilla.org/en-US/firefox/addon/colorlicious/?src=search