sphinx_nervproject_theme/sphinx_nervproject_theme/util/extlinks.html

{# external links, i.e. #}
{% if theme_external_links %}
  {% for (label, url) in theme_external_links %}
    <div class="nav-item">
      <a href="{{ url }}"
        class="nav-link external">
          {{ label }} <outboundlink/>
      </a>
    </div>
  {% endfor %}
{% endif %}