/**
  * Style attribute for event bg color
  */
 public function get_category_text_color(Ai1ec_Event $event)
 {
     $category_text_color = null;
     $categories = $this->_taxonomy_model->get_post_categories($event->get('post_id'));
     if (!empty($categories)) {
         $category_text_color = $this->get_event_category_text_color($categories[0]->term_id, $event->is_allday() || $event->is_multiday());
     }
     return $category_text_color;
 }