cookiecutter-data-science/toc.html

<div class="bs-sidebar hidden-print affix well" role="complementary">
    <ul class="nav bs-sidenav">
    {% for toc_item in toc %}
        <li class="first-level {% if toc_item.active %}active{% endif %}"><a href="{{ toc_item.url }}">{{ toc_item.title }}</a></li>
        {% for toc_item in toc_item.children %}
            <li class="second-level"><a href="{{ toc_item.url }}">{{ toc_item.title }}</a></li>
            {% for toc_item in toc_item.children %}
                <li class="third-level"><a href="{{ toc_item.url }}">{{ toc_item.title }}</a></li>
            {% endfor %}
        {% endfor %}
    {% endfor %}
    </ul>
</div>