/**
  * @param array $arrIds
  * @return array
  */
 protected function getCssStyleSelectorClassesByIds(array $arrIds)
 {
     if (empty($arrIds)) {
         return array();
     }
     $arrClasses = CssStyleSelectorModel::findCssClassesByIds($arrIds);
     return $this->convertCombinedClassesToSingleClasses($arrClasses);
 }