info-slash/cinder/toc.html

<div class="bs-sidebar hidden-print affix well" role="complementary">
    <ul class="nav bs-sidenav">
        {%- for toc_item in page.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>