Might you like Pale Moon
I couldn't get firefox to display FULL BLACK in youtube -- 16-235 I guess, maybe much brighter. Anyway, I didn't like the interface much either, and Palemoon looks great!
Give it a go!
I tried Pale Moon recently, but I had rendering problems on pages that I need to look at every day. I've tried them all. I used to prefer Pale Moon, but I faded away from it for some reason and today I'm glad that happened because I would have gone back to Firefox out of frustration anyway due to these rendering issues.
So, thank you, but I'm all set.