Formatting component to alter fg/bg colors for each segment

[Barbaross93]

I'm trying to modify the buffer component so that it can display different background/foreground colors between the buffer's index and the buffer's name when using mode = 2. I'm not really sure how to do this other than some fmt function? My lua skills aren't strong so I'm unsure how to write such a function.

I've attached a screen shot to demonstrate what I mean:

This was done with cokeline. Unfortunately, cokeline doesn't have a way to show tab information so I'm trying to achieve my goals through lualine instead.