All that being said, just using the new UI out of the box actually looks great to me too: https://i.imgur.com/WUaiRUV.png

I never wanted a carbon copy of Chrome, just something that looked good, so I'm glad to see Firefox provide a nicer default experience and add its own unique style. It's actually pretty similar to MaterialFox anyway, aside from the "floating" tab style and slightly higher vertical space usage.