Needs to be ".tab.last-active .background" instead due to some change in TST a while ago.

Unfortunately it marks new tabs that I open even though I didn't visit them yet.
If I don't open anything new, it works as intended, I suppose.

I get lost on what tab I was working on when needed to switch due to interruption. Now this extensions helps to point me where I was.

What I'd really appreciate would be access to bit more history, e.g.:
.tab.last-active2
.tab.last-active3
...
.tab.last-active5

I used to use aging-tabs extension with fading background of older tabs the above would help to bring back this functionality.