{% macro renderNav(items) %}
  <ul>
  {% for item in items %}
    <li>
      <a href="{{ item.path }}">{{ item.page.title }}</a>
      {% if item.children and item.children.length %}
        {{ renderNav(item.children) }}
      {% endif %}
    </li>
  {% endfor %}
  </ul>
{% endmacro %}

<aside class="sidebar" id="sidebar">
  <nav>
    {{ renderNav(navigation) }}
  </nav>
</aside>