Safari doesn't look anywhere close to that on Big Sur. Also in Fx active tabs look inactive (active one is dark grey, inactive is light grey), which totally contradicts Safari where it is exactly the other way round (and it pretty much has been the other way round in all apps on all systems I've been using the last 20 years)

Hey,
I really like this theme on my new big sur machine.
however, the tab colors are different compared to safari. On safari, the active tab has a lighter color, and the inactive tabs have a darker color. This is reversed in this theme.
I'd enjoy it even more if this theme would honor that. The experience would be seamless and you won't wonder whats the active tab when you have to switch between both browser regularly.