private function splitIntoRules($css)
	{
		$rules = preg_split('/}/', trim($this->stripComments($css)));

		// complete any rules by append } to them
		array_walk($rules,
			function (&$s) {
				!empty($s) && $s = trim("$s}");
			});

		// clears out any empty rules
		return array_filter($rules);
	}