This module is a re-implementation aiming for speed instead of maximum
compression, so it can be used at runtime (rather than during a
preprocessing step). RCSSmin does syntactical compression only (removing
spaces, comments and possibly semicolons). It does not provide semantic
compression (like removing empty blocks, collapsing redundant properties
etc). It does, however, support various CSS hacks (by keeping them
working as intended).

WWW: https://github.com/ndparker/rcssmin