site/_includes/docs_ul.html

{% assign items = include.items %}

<ul>
{% for item in items %}
  {% comment %} Account for the baseurl to make sure we compare the full URI. {% endcomment %}
  {% capture item_url %}{{site.baseurl}}{{ item | prepend:"/docs/" | append:".html" }}{% endcapture %}
  {% capture item_url2 %}{{site.baseurl}}{{ item | prepend:"/docs/" | append:"/" }}{% endcapture %}
  {% capture current_url %}{{ site.baseurl }}{{ page.url }}{% endcapture %}

  {% if item_url == current_url %}
    {% assign c = "current" %}
  {% else %}
    {% assign c = "" %}
  {% endif %}

  {% for p in site.docs %}{% comment %}
    {% endcomment %}{% capture p_url %}{{site.baseurl}}{{p.url}}{% endcapture %}{% comment %}
    {% endcomment %}{% if p.sidebar_title != nil %}{% comment %}
      {% endcomment %}{% assign anchor_text = p.sidebar_title %}{% comment %}
    {% endcomment %}{% else %}{% comment %}
      {% endcomment %}{% assign anchor_text = p.title %}{% comment %}
    {% endcomment %}{% endif %}{% comment %}
    {% endcomment %}{% if p_url == item_url or p_url == item_url2 %}{% comment %}
      {% endcomment %}<li class="{{ c }}"><a href="{{ p_url }}">{{ anchor_text }}</a></li>{% comment %}
      {% endcomment %}{% break %}{% comment %}
    {% endcomment %}{% endif %}{% comment %}
  {% endcomment %}{% endfor %}

{% endfor %}
</ul>