The minifier is based on the semantics of the YUI compressor, which itself is
based on the rule list by Isaac Schlueter. 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).