cycat-project-website/_includes/main-menu.html

<div id="main-menu" class="main-menu">
  <ul>
    <li><a href="{{site.baseurl}}/" class="{% if page.url == '/' %}current{% endif %}">Home</a></li>
    <li><a href="{{site.baseurl}}/services/" class="{% if page.url contains 'services' %}current{% endif %}">Services</a></li>
    <li><a href="{{site.baseurl}}/team/" class="{% if page.url contains 'team' %}current{% endif %}">Team</a></li>
    <li><a href="{{site.baseurl}}/testimonials/" class="{% if page.url contains 'testimonials' %}current{% endif %}">Testimonials</a></li>
    <li><a href="{{site.baseurl}}/contact/" class="{% if page.url contains 'contact' %}current{% endif %}">Contact</a></li>
  </ul>
</div>