oliverdavies.uk/source/_partials/navbar.html.twig

<nav class="navbar navbar-inverse navbar-fixed-top">
  <div class="container">
    <div class="navbar-header">
      <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#navbar" aria-expanded="false" aria-controls="navbar">
        <span class="sr-only">Toggle navigation</span>
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
      </button>
      <a class="navbar-brand" href="/">{{ site.title }}</a>
    </div>

    <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>
        {% endfor %}
      </ul>
    </div>{# .nav-collapse #}
  </div>
</nav>