Bootstrap/docs/_includes/nav/docs.html

<header class="navbar navbar-static-top bs-docs-sidebar" id="top" role="banner">
  <div class="container-fluid">
    <div class="navbar-header">
      <button class="navbar-toggle" type="button" data-toggle="collapse" data-target=".bs-sidenav-collapse">
        <span class="sr-only">Toggle navigation</span>
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
      </button>
      <a href="../" class="navbar-brand">
        Bootstrap
      </a>
    </div>
    <nav class="collapse navbar-collapse bs-sidenav-collapse" role="navigation">
      <div class="bs-docs-toc-item{% if page.slug == "getting-started" %} active{% endif %}">
        <a class="bs-docs-toc-link" href="../getting-started">Getting started</a>
        {% if page.slug == "getting-started" %}
        <ul class="nav bs-docs-sidenav">
          {% include nav/getting-started.html %}
        </ul>
        {% endif %}
      </div>
      <div class="bs-docs-toc-item{% if page.slug == "css" %} active{% endif %}">
        <a class="bs-docs-toc-link" href="../css">CSS</a>
        {% if page.slug == "css" %}
        <ul class="nav bs-docs-sidenav">
          {% include nav/css.html %}
        </ul>
        {% endif %}
      </div>
      <div class="bs-docs-toc-item{% if page.slug == "components" %} active{% endif %}">
        <a class="bs-docs-toc-link" href="../components">Components</a>
        {% if page.slug == "components" %}
        <ul class="nav bs-docs-sidenav">
          {% include nav/components.html %}
        </ul>
        {% endif %}
      </div>
      <div class="bs-docs-toc-item{% if page.slug == "js" %} active{% endif %}">
        <a class="bs-docs-toc-link" href="../javascript">JavaScript</a>
        {% if page.slug == "js" %}
        <ul class="nav bs-docs-sidenav">
          {% include nav/javascript.html %}
        </ul>
        {% endif %}
      </div>
      <div class="bs-docs-toc-item{% if page.slug == "customize" %} active{% endif %}">
        <a class="bs-docs-toc-link" href="../customize">Customize</a>
        {% if page.slug == "customize" %}
        <ul class="nav bs-docs-sidenav">
          {% include nav/customize.html %}
        </ul>
        {% endif %}
      </div>
      <div class="bs-docs-toc-item{% if page.slug == "js" %} active{% endif %}">
        <a class="bs-docs-toc-link" href="../about">About</a>
        {% if page.slug == "js" %}
        <ul class="nav bs-docs-sidenav">
          {% include nav/about.html %}
        </ul>
        {% endif %}
      </div>
    </nav>
  </div>
</header>