webtheme_admin-11.0.x-dev/templates/navigation/container--administration-menu.html.twig

{#
/**
 * @file
 * Specific container for Gin Toolbar module, which relies on this markup.
 *
 * Available variables:
 * - attributes: HTML attributes for the containing element.
 * - children: The rendered child elements of the container.
 * - has_parent: A flag to indicate that the container has one or more parent
     containers.
 *
 * @see template_preprocess_container()
 *
 * @ingroup themeable
 */
#}
{%
  set classes = [
    has_parent ? 'js-form-wrapper',
    has_parent ? 'form-wrapper',
  ]
%}
<div{{ attributes.addClass(classes) }}>{{ children }}</div>