mkdocs-material/material/partials/tabs-item.html

<li class="md-tabs__item">
  {% if nav_item.children and nav_item.children | length > 0 %}
  <a href="{{ nav_item.children[0].url }}" title="{{ nav_item.title }}" class="md-tabs__link {% if nav_item.active %} md-tabs__link--active {% endif %}">
    {{ nav_item.title }}
  </a>
  {% elif nav_item.url == base_url %}
    <a href="{{ nav_item.url }}" title="{{ nav_item.title }}" class="md-tabs__link {% if nav_item.active %} md-tabs__link--active {% endif %}">
      {{ nav_item.title }}
    </a>
  {% endif %}
</li>