code: public function addGrid16CSS(\PageModel $objPage, \LayoutModel $objLayout, \PageRegular $objPageRegular)
      {
          /*
           * vor internen laden
           * $GLOBALS['TL_CSS'][]  = 'assets/contao-grid16/css/grid-1120-16-pixel.min.css';
           * nach den anderen
           * $GLOBALS['TL_HEAD'][] = '<link ...>';
           */      
          
          $arrFrameworkGrid16 = \StringUtil::deserialize($objLayout->frameworkGrid16);
          
          // Add the Grid16 CSS framework style sheets
          if (is_array($arrFrameworkGrid16))
          {
              foreach ($arrFrameworkGrid16 as $strFile)
              {
                  if ($objLayout->loadingOrderGrid16 == 'before_framework') 
                  {
                      $GLOBALS['TL_CSS'][] = 'bundles/bugbustergrid16/' . basename($strFile, '.css') . '.min.css';
                  }
                  else 
                  {
                      $GLOBALS['TL_HEAD'][] = '<link rel="stylesheet" href="bundles/bugbustergrid16/' . basename($strFile, '.css') . '.min.css">';
                  }
                  
              }
          }
          
          return;
      }
docs: Hook loadDataContainer, add Grid16 CSS
  
  @param PageModel   $objPage
  @param LayoutModel $objLayout
  @param PageRegular $objPageRegular