A simple script to minify (multiple) CSS files.

cssmin.py

import sys, re

css = ""
saveFileName = "default.css"
flag = False;
for n, i in enumerate(sys.argv):
    if n == 0:
        pass
    elif i == "-h":
        print "Add CSS files space seperated to be combined and minified. Add -s followed by the name of the new CSS file."
        break
    elif i == "-o":
        flag = True
    elif flag:
        saveFileName = i
        flag = False
    else:
        css = css + open( i, 'r' ).read()

# remove comments - this will break a lot of hacks :-P
css = re.sub( r'\s*/\*\s*\*/', "$$HACK1$$", css ) # preserve IE<6 comment hack
css = re.sub( r'/\*[\s\S]*?\*/', "", css )
css = css.replace( "$$HACK1$$", '/**/' ) # preserve IE<6 comment hack

# url() doesn't need quotes
css = re.sub( r'url\((["\'])([^)]*)\1\)', r'url(\2)', css )

# spaces may be safely collapsed as generated content will collapse them anyway
css = re.sub( r'\s+', ' ', css )

# shorten collapsable colors: #aabbcc to #abc
css = re.sub( r'#([0-9a-f])\1([0-9a-f])\2([0-9a-f])\3(\s|;)', r'#\1\2\3\4', css )

# fragment values can loose zeros
css = re.sub( r':\s*0(\.\d+([cm]m|e[mx]|in|p[ctx]))\s*;', r':\1;', css )

for rule in re.findall( r'([^{]+){([^}]*)}', css ):

    # we don't need spaces around operators
    selectors = [re.sub( r'(?<=[\[\(>+=])\s+|\s+(?=[=~^$*|>+\]\)])', r'', selector.strip() ) for selector in rule[0].split( ',' )]

    # order is important, but we still want to discard repetitions
    properties = {}
    porder = []
    for prop in re.findall( '(.*?):(.*?)(;|$)', rule[1] ):
        key = prop[0].strip().lower()
        if key not in porder: porder.append( key )
        properties[ key ] = prop[1].strip()

    # output rule if it contains any declarations
    if properties:
        f = open(saveFileName,'a')
        f.write("%s{%s}" % ( ','.join( selectors ), ''.join(['%s:%s;' % (key, properties[key]) for key in porder])[:-1] ) )
        f.close()

An example usage:

python cssmin.py -o main.css bootstrap.css corgi.css tooltipster.css elusive-webfont.css