dsfr4drupal-1.x-dev/layouts/layout_discovery/onecol/layout--onecol.html.twig

{% if content %}
  {% if attributes is not empty %}
    <div{{ attributes }}>
  {% endif %}

  <div {{ region_attributes.content.addClass('layout__region', 'layout__region--content') }}>
    {{ content.content }}
  </div>

  {% if attributes is not empty %}
    </div>
  {% endif %}
{% endif %}