Added variables for some colors
Updated comments and selftext visited link color
Introduced break point mixin

Added in new Mixins partial
Added grouping of media queries in post-processing
Replaced Wide media query for inlined ones
Further moved Media Queries from partial...

…to each inlined element declaration.
Disable-by-default: Media Queries grouping

Currently the `group-css-media-query` library doesn’t support sorting
by min-width, which is needed for Reeddit’s styles.