rivet-1.0.x-dev/templates/block/block--region-sidebar.html.twig

{% if content %}
{{ attach_library('rivet/rvt-c-sidenav')}}
<div{{attributes.addClass('rvt-sidenav')|without('id')}}>
  {{ title_prefix }}
  {% if label %}
    <span{{title_attributes.addClass('rvt-sidenav__label')}}>
    {{ label }}
    </span>
  {% endif %}
  {{ content }}
  {{ title_suffix }}
</div>
{% endif %}