notifications-admin/app/templates/components/branding-preview.html

{% macro branding_preview(branding_style, endpoint) %}
  <iframe src="{{ url_for(endpoint, branding_style=branding_style) }}" class="branding-preview" scrolling="no"></iframe>
{% endmacro %}

{% macro email_branding_preview(branding_style) %}
  {{ branding_preview(branding_style, 'main.email_template') }}
{% endmacro %}

{% macro letter_branding_preview(branding_style) %}
  {{ branding_preview(branding_style, 'main.letter_template') }}
{% endmacro %}