public function get_diff() {
		if (!$this->output_css_plain) {
			$this->formatted();
		}

		$diff = strlen($this->output_css_plain) - strlen($this->input_css);

		if ($diff > 0) {
			return '+' . $diff;
		} elseif ($diff == 0) {
			return '+-' . $diff;
		}

		return $diff;
	}