at_theme-1.4.1/at_core/templates/layout/maintenance-page.html.twig

{#
/**
 * @file
 * Theme override to display a single Drupal page while offline.
 *
 * @see template_preprocess_maintenance_page()
 */
#}
<div class="page maintenance-page">

  <header class="l-pr page__row pr-header" id="masthead">
    <div class="site-branding">

      {% if logo %}
        <a href="{{ front_page }}" title="{{ 'Home'|t }}" rel="home" class="site-branding__logo-link">
          <img src="{{ logo }}" alt="{{ 'Home'|t }}" class="site-branding__logo-img"/>
        </a>
      {% endif %}

      {% if site_name or site_slogan %}
        <span class="site-branding__text">
          {% if site_name %}
            <strong class="site-branding__name">
             <a href="{{ front_page }}" title="{{ 'Home'|t }}" rel="home" class="site-branding__name-link">{{ site_name }}</a>
            </strong>
          {% endif %}
          {% if site_slogan %}
            <em class="site-branding__slogan">{{ site_slogan }}</em>
          {% endif %}
        </span>
      {% endif %}

    </div>
  </header>

  <main class="l-pr page__row pr-main" id="main-content">
    {% if title %}
      <h1 class="page__title">{{ title }}</h1>
    {% endif %}
    {{ page.content }}
  </main>

</div>