protected function cssPipeline()
	{
		// If a custom minifier has been set use it, otherwise fallback to default
		$minifier = (isset($this->css_minifier)) ? $this->css_minifier : function ($buffer) {
			$min = new \CSSmin();
			return $min->run($buffer);
		};

		return $this->pipeline($this->css, '.css', $this->css_dir, $minifier);
	}