JavascriptCSSMinifier.js

/**
 * Minify CSS
 * @param  string css text
 * @return sting minified css text
 * @author awan <nawa@yahoo.com>
 */
function minifyCSS(text)
{
    // check if css is string values
    if (typeof text != 'string') {
        return null;
    }
    return text
            // repacle  comment, tab and new line
            .replace(/(\/\*(?:(?!\*\/)[\s\S])*\*\/|[\r\n\t]+)/gm, '')
            // replace multiple spaces with single spaces
            .replace(/ {2,}/g, ' ')
            // remove spaces after / brefore colon , semicolon and commas
            .replace(/(?:(?: )?([{:}]|[;,]) )/g, '$1')
            // remove semicolon if nearest of brackets
            .replace(/\s*;\s*(})\s*/g, '$1')
            // replace some spaces
            .replace(/\s*([*$~^|]?=|[{};,>~+-]|\s+!important\b)\s*/gi, '$1')
            // replaces some spaces inside brackets and colon
            .replace(/([[(:])\s+|\s+([\]\)])|\s+(:)\s+/g, '$1$2$3')
            // shorthand of hex color like #ffffff to #fff
            .replace(/(\#((?:[a-f0-9]){3}))(\2)?\b/gi, '$1')
            // shorthand replace muleiple twice hex color like #ddeeff to #def
            .replace(/(#(?:([a-f0-9]){1}(?:\2)([a-f0-9]){1}(?:\3))([a-f0-9]){1}(?:\4))\b/gi, '#$2$3$4')
            // trimming start or end css
            .replace(/(^\s*)|(\s*$)/, '');
}

if you need PHP version that combine or minify css follow this link:

https://github.com/aufa/CssJsCombine