parseCSS.js // returns parsed CSS text as a JavaScript object

parseCSS.js

(function (global) {
	function clean(css) {
		return css
		.replace(/\/\*[\W\w]*?\*\//g, "") // remove comments
		.replace(/^\s+|\s+$/g, "") // remove trailing spaces
		.replace(/\s*([:;{}])\s*/g, "$1") // remove trailing separator spaces
		.replace(/\};+/g, "}") // remove unnecessary separators
		.replace(/([^:;{}])}/g, "$1;}") // add trailing separators
	}

	function refine(css, isBlock) {
		return /^@/.test(css) ? (css = css.split(" ")) && {
			"identifier": css.shift().substr(1).toLowerCase(),
			"parameters": css.join(" ")
		} : (isBlock ? /:$/ : /:/).test(css) ? (css = css.split(":")) && {
			"property": css.shift(),
			"value": css.join(":")
		} : css;
	}

	function parse(css, regExp, object) {
		for (var m; (m = regExp.exec(css)) != null;) {
			if (m[2] == "{") object.block.push(object = {
				"selector": refine(m[1], true),
				"block": [],
				"parent": object
			});
			else if (m[2] == "}") object = object.parent;
			else if (m[2] == ";") object.block.push(refine(m[1]));
		}
	}

	global.parseCSS = function (css) {
		return parse(clean(css), /([^{};]*)([;{}])/g, css = { block: [] }), css;
	};
})(this);

parseCSS.min.js

(function(e){function t(e){return e.replace(/\/\*[\W\w]*?\*\//g,"").replace(/^\s+|\s+$/g,"").replace(/\s*([:;{}])\s*/g,"$1").replace(/\};+/g,"}").replace(/([^:;{}])}/g,"$1;}")}function n(e,t){return/^@/.test(e)?(e=e.split(" "))&&{identifier:e.shift().substr(1).toLowerCase(),parameters:e.join(" ")}:(t?/:$/:/:/).test(e)?(e=e.split(":"))&&{property:e.shift(),value:e.join(":")}:e}function r(e,t,r){for(var i;(i=t.exec(e))!=null;)i[2]=="{"?r.block.push(r={selector:n(i[1],!0),block:[],parent:r}):i[2]=="}"?r=r.parent:i[2]==";"&&r.block.push(n(i[1]))}e.parseCSS=function(e){return r(t(e),/([^{};]*)([;{}])/g,e={block:[]}),e}})(this)

@leomelzer, you are correct. css is redefined and then returned.