Feature request: show tab numbers only when alt is pressed

[MAHcodes]

Hi this is a great mod, appreciate your work!

I was wondering if it might be possible to add an option so that tab numbers only show when the Alt key is pressed? I'm trying to keep the tab bar clean, but still want quick access to the numbers when needed.

I came across this chrome css hack that toggles the tab bar visibility with the Alt key, so maybe something similar could work here?

[Jellie06]

I would also appreciate this if possible