This is a heavy regex-based removal of whitespace, unnecessary
comments and tokens, and some CSS value minimization, where practical.
Many steps have been taken to avoid breaking comment-based hacks,
including the ie5/mac filter (and its inversion), but expect tricky
hacks involving comment tokens in 'content' value strings to break
minimization badly. A test suite is available.
Note: This replaces a lot of spaces with line breaks. It's rumored
(https://github.com/yui/yuicompressor/blob/master/README.md#global-options)
that some source control tools and old browsers don't like very long lines.
Compressed files with shorter lines are also easier to diff. If this is
unacceptable please use CSSmin instead.