Double colour for backgrounds, and rest of the grounds

So, alot of backgrounds have surface part, and sky part. They both share the same colour, so my suggestion is to make backgrounds doublecolored.
And for "wall" backgrounds and most of the old grounds, Rob can think of how it could look like.


EDIT:
Forgot to mention, any level created before this would be implemented, would have a "Legacy Background/ground" which are just simply backgrounds/grounds that still use one color.