public function getBodyStyles(core_kernel_classes_Resource $itemResource, $langCode = ''){
        $itemContent = $this->getItemContent($itemResource, $langCode);
        if(is_null($itemContent)){
            throw new \common_Exception('cannot find valid qti item content');
        }else{
            $classAttr = (string) $itemContent->itemBody['class'];
            preg_match_all('/x-tao-style-'.self::STYLE_NAME_PATTERN.'/', $classAttr, $matches);
            if(isset($matches[1])){
                return $matches[1];
            }
        }
    }