web2019/templates/shortcodes/layout_centered_content.html

<div class="{% if css %}{{ css }}{% else %}row d-flex align-items-center mt-5 mb-5{% endif %}">

  <div class="{% if min_width %}col-12 col-md-8 mx-auto{% else %}col-12{% endif %} text-center">

    {{ body | markdown | safe }}

  </div>

</div>