protected function render ()
  {
    $prop = $this->props;
    if (exists ($prop->src))
      $this->context->getAssetsService ()->addStylesheet ($prop->src, $this->props->prepend);
    else if ($this->hasChildren ())
      $this->context->getAssetsService ()->addInlineCss (self::getRenderingOfSet ($this->getChildren ()), $prop->name,
        $this->props->prepend);
  }