public static function addCommonStylesheets($commonStylesheets)
    {
        foreach (GeneralUtility::trimExplode(',', $commonStylesheets, true) as $commonStylesheet) {
            $commonStylesheet = self::resolveUrl($commonStylesheet);
            if ($commonStylesheet) {
                self::$commonStylesheets[] = $commonStylesheet;
            }
        }
    }