Why I do have to install an addon, which restores something, what IMO everyone on this thread and probably most people out there would love having as native? Namely not flat-design visually easy to parse tabs! Any occurence of flat-design stuff on software, which is used day by day, was and is awkward, because it causes displeasure and it is more time- and eye-consuming.

Oh, the new theme isn't bad. Just a bit of a shock as I was in another window and suddenly noticed FF's UI overhaul.