function(c,r){                                   // c = css code, r = placeholder for "replace"
  return 
  c[r='replace'](/((\/\*[^]*?\*\/)|\s)+/g,' ')   // replace all comments and spaces, tabs, line breaks with one space
   [r](/^ | $|[ ;]*([^\w.#) ]) *| (\))/g,'$1$2') // remove spaces around every "safe character": { } ; , : ! + > ~ ( - @, remove semicolon before }, and keep one space between ) and "unsafe characters": a-z A-Z 0-9 # . (for old IE compatibility)
   [r](/(\D)((0)[a-z%]+|0(\.))/gi,'$1$3$4')      // remove leading zero and unit after 0
}