_includes/mainmenu.html

{% assign activeMenu = nil %}
<nav class="mainmenu">
    <ul>
    {% for link in site.navigation %}
		{% assign url = page.url|remove:'/index.html' %}
    	{% assign active = nil %}
        {% assign linkurl = link.url|remove:'/index.html' %}
        {% assign linkurl = link.url|remove:'/index.md' %}
		<!-- {{ linkurl }} || {{ url }} -->
    	{% if url == "" and link.url == "/" %}
    		{% assign active = 'active' %}
    	{% elsif url == link.url or page.url == link.url %}
    		{% assign active = 'active' %}
        {% elsif url == linkurl %}
    		{% assign active = 'active' %}
    	{% elsif page.layout == link.layout %}
    		{% assign active = 'active' %}
    	{% elsif page.post == true and link.layout == 'post' %}
    		{% assign active = 'active' %}
    	{% else %}
    		{% for sublink in link.subnavigation %}
    			{% if url == sublink.url %}
    				{% assign active = 'active' %}
    			{% endif %}
    		{% endfor %}
    	{% endif %}
    	{% if active == "active" %}
    		{% assign activeMenu = link %}
    	{% endif %}
        {% unless link.url contains "http://" %}
            {% capture url %}{{ site.baseurl }}{{ link.url}}{% endcapture %}
        {% else %}
            {% assign url = link.url %}
        {% endunless %}
    	<li class="{{ active }}"><a href="{{ url }}">{{ link.text }}</a></li>
    {% endfor %}
    </ul>
</nav>