{% set target = preview_url or c.preview_url %}
<a
  class="btn pull-right"
  style="margin-bottom: 10px;"
  href="{{ target }}"
  target="_blank">
  {{ _('See Externally') }}
</a>
<iframe
  src="{{ target }}"
  style="height: 600px; width: 100%; border: none;"
  allowFullScreen mozAllowFullScreen webkitAllowFullScreen>
</iframe>