One of the best thins in the new FF to me though (also macos). I still hope apple will to something to their gray ui. I'd love to have dark theme for the ui, not only for menubar and dock.
https://developer.apple.com/library/content/documentation/Ge...
Haven't seen any other black title bar on my Mac though...
Dark is the default for the Developer Edition, which is what you're thinking of. But Normal is the default for Stable. Light is almost the same as Normal, but with a few more elements in white.
I was under the impression Apple didn't allow any web rendering engines on iOS except the one mobile Safari uses, thus Chrome, Firefox, etc, on iOS are just wrappers around the Safari engine. Is that not the case anymore? It would be nice to see these speedups on iOS.
Also note their updated Firefox on iOS. It looks and works just fine now and comes with Firefox Sync which gives you access to your tabs, bookmarks and history.