Background color config issues

[LiHRaM]

I decided to configure wldash to match my theme, using the following settings:

background:
  red: 233.0
  green: 228.0
  blue: 226.0
  opacity: 0.9

This seems to really mess with the font rendering.

[kennylevinsen]

Values are between 0.0 and 1.0, so you're asking for 23300% red, 22800% green and 22600% blue. Should probably have thrown an error instead of breaking all the blending calculations though...

[LiHRaM]

Okay. Yeah, throwing an error for invalid ranges makes sense. I'll submit a PR. :)