kyopages/theme/mkdocs/nav-sub.html

{%- if not nav_item.children %}
<li {% if nav_item.active %}class="active"{% endif %}>
    <a href="{{ nav_item.url }}">{{ nav_item.title }}</a>
</li>
{%- else %}
  <li class="dropdown-submenu">
    <a href="#">{{ nav_item.title }}</a>
    <ul class="dropdown-menu">
        {%- for nav_item in nav_item.children %}
            {% include "nav-sub.html" %}
        {%- endfor %}
    </ul>
  </li>
{%- endif %}