Feature request: ability to customize icons of pinned tabs

[JustAdreamerFL]

I am retarded and in need of this feature.

To be exact,

I reguraly use 3 different mail accounts on the same mail website (gmail). I am retarded because I can't remember in what order I put them, so I waste few secconds every time I am looking for some mail.
It would be amazing to easily distinguish between pinned tabs from the same website that contain different content by giving the tab a custom icon or image to represent each pinned tab.

I know that there is an extension for this, but think about the joy of a simple man who doesn't know that it exists. He would only knew that it exists in Zen. He would be hooked.