Not good for FF ESR Rated 1 out of 5 stars
This worked great until my company updated to FF ESR 10.0.11. I had been using ColorfulTabs since I had the option to set a color per tab. That was taken away on newer versions. I wasn't able to have it on my new laptop, but somehow I kept it on my work installation.
Then ESR 10.0.11 happened, FF tells me the update is compatible, but nothing happens. I've tried setting the color by domain, setting by default, and setting by random, all to no avail.