I really liked colorful tabs and I very much appreciate the developer's attempts, against difficult odds, to get it working on the new Firefox 57. It's not at a useful point for me as yet, though. I'll keep trying it again as new versions come out.

I would respond to phubert's comment about going over to Chrome by saying that, over many years, I have never managed to get the Chrome developers to listen to any issues I have had with it and so I'm trying hard to stick with Firefox despite its current drawbacks.