mkdocs-material/material/toc-item.html

<li class="md-nav__item">
  <a href="{{ toc_item.url }}" title="{{ toc_item.title }}" class="md-nav__link">
    {{ toc_item.title }}
  </a>
  {% if toc_item.children %}
    <ul class="md-nav__list">
      {% for toc_item in toc_item.children %}
        {% include "toc-item.html" %}
      {% endfor %}
    </ul>
  {% endif %}
</li>