public function set($css, $value = NULL) {

		$css = trim(strtolower($css));


		if (func_num_args() == 1) {

			$elements = explode(';', $css);

			foreach ($elements as $element) {

				if (!$element = trim($element)) {
					continue;
				}

				$element = explode(':', $element);

				if (!$element[0] = trim(@$element[0])) {
					continue;
				}

				$element[1] = trim(@$element[1]);

				$this->set($element[0], $element[1]);
			}

			return;
		}

		$css = strtolower($css);
		$this->css[$css] = $value;
		return $this;
	}