Redesign: Expand color palette for Astro
Some theme colors were defined on eclipse.org's redesign which could be brought over to Astro. Specifically the color variables and background color classes.
The bg color LESS generator functions may also no longer be needed, as we need more control over the colors.
The generator functions were simply applying a darken(10%)
or lighten(10%)
. But that was too simple in most cases.