Looks like changing line 94 in frame.lua did something.
Code:
health.bg:SetVertexColor(r * healthBG, g * healthBG, b * healthBG)
to
health.bg:SetVertexColor(255, 0, 0)
Now the background is red, so i guess that worked.
Edit: OK so i pretty much figured out everything, except how i can change the color on the healthtext. Seems to be class colored like the name. Any suggestions?