It looks identical to my Firefox except the + is on the other side. The icons are the same. (I have a userChrome.css that removes all the dumbass padding newer releases of Firefox added.)
I've found running 4K @ 2x/200% scaling "retina" to be the best price/performance option right now. 5K displays are nowhere to be seen and 6K/8K have absurd prices.
My dream monitor would be a dual-5k super-ultrawide, even at 60Hz. That's at least 5 years away if not 10.