Source: apc-static/lib/minify/minify_css_string.js

/**
 * Minify css string.
 * @function lib.minify.minifyCssString
 * @param {string} src - Source css string.
 * @param {function} callback - Callback when done.
 * @author Taka Okunishi
 *
 */

module.exports = function (src, callback) {
    var CleanCSS = require('clean-css');
    var minimized = new CleanCSS().minify(src);
    callback(null, minimized);
};