Hi Aviana,
First of all, thank you for your work!
Currently, when I have a healthbar of any frames set to inverted, they show as black when in range and full. This makes it pretty much impossible to tell what class a unit is when its health is full, which is useful (e.g. dispelling mana burn on mana classes on Baron Geddon). However, when the unit is out of range, the background (full bar) is slightly coloured to its class colour so that warlock is a little bit purple. hunter is green etc. Would it be possible to have that slight bar colouring when the unit is in range as well, instead of it being black? This would make the decision-making process much easier and I think it just looks better.
This functionality is embedded in Shadowed Unit Frames, which I believe is the basis for Luna, and I think I've narrowed the code down to "layout.lua" in the modules folder, but my casual programming skills prevent me from editing the code to work on my own.

Kind regards,
pingwinho

Somewhat related: I've tried changing the code to do a proper invert instead of "Kind of inverts the color scheme", by passing the configured background alpha and reading the value in overrides.lua. But the health bar is still layered on top of the background, so you can't simply replace element:SetStatusBarColor(0, 0, 0, 1) with element:SetStatusBarColor(r, g, b, element.colorInvertAlpha).
I guess inverting needs to be implemented in oUF itself for it to work.