Add active styling programatically

source/themes/opdavies/oliverdavies/_layouts/default.twig

@@ -44,7 +44,7 @@
                 <div id="navbar" class="collapse navbar-collapse" role="navigation">
                     <ul class="nav navbar-nav navbar-right">
                         {% for link in site.main_menu %}
-                            <li class="nav__{{ link.title|lower }}"><a href="{{ link.href }}">{{ link.title }}</a></li>
+                            <li class="nav__{{ link.title|lower }}{% if page.url ~ '/' == link.href %} active{% endif %}"><a href="{{ link.href }}">{{ link.title }}</a></li>
                         {% endfor %}
                     </ul>
                 </div>{# .nav-collapse #}