Finally I can see the active tab.
It actually installs two versions, very similar to each other.
One is "firefox alpenglow", and the other is "firefox radiance" which is my favorite.

the best firefox theme

I adore this theme's color palette! It's easy on my sensitive eyes, melds well from pink to purple, and best of all? It's my two favorite colors: pink and purple! All in all, it's cute, adorable, and adds a nice pop of personality and colour to my browser firefox thingy.