leftnav.html

<div class="leftnav">
  <ul class="nav nav-list">
{% for group in page.nav %}
  {% capture group_url %}/{{ page.name }}/{{ group.url }}{% endcapture %}
  <li class="nav-header{% if page.url == node_url %} active{% endif %}">
    {% if page.url %}
      <a href="{{group.url}}">{{group.name}}</a>
    {% else %}
      {{group.name}}
    {% endif %}
  </li>
  {% for node in group.articles %}
    {% capture node_url %}/{{ page.name }}/{{ node.url }}{% endcapture %}
    {% if page.url == node_url %}
      <li class="active"><a href="{{node.url}}">{{node.title}}</a></li>
    {% else %}
      <li><a href="{{node.url}}">{{node.title}}</a></li>
    {% endif %}
  {% endfor %}
{% endfor %}
  </ul>
  <hr />
  <div class="license">
    <a rel="license" href="http://creativecommons.org/licenses/by-sa/4.0/"><img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by-sa/4.0/80x15.png" /></a>
  </div>
</div>