nav.html

<nav class="navbar fixed-top d-flex align-items-center navbar-expand-lg navbar-dark bg-primary justify-content-between">
  <div class="container">
    <a class="d-flex align-items-center navbar-brand logo" href="{{ "/" | relative_url }}">
      <img class="mr-3" src="{{ "/img/clair-cloud-white.svg" | relative_url }}"/>
      {{ site.title }}
    </a>
    <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
      <i class="fas fa-bars"></i>
    </button>

    <div class="collapse navbar-collapse" id="navbarSupportedContent">
      <ul class="navbar-nav ml-auto">
        {% for item in site.data.nav.links %}
        {% if item.submenu %}
        <li class="nav-item dropdown">
          <a class="nav-link dropdown-toggle" href="#" id="{{ item.title | slugify }}" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
            {{ item.title }}
          </a>
          <div class="dropdown-menu" aria-labelledby="{{ item.title | slugify }}">
            {% for subitem in item.submenu %}
            <a class="dropdown-item" href="{{ subitem.url | relative_url }}">{{ subitem.title }}</a>
            {% endfor %}
          </div>
        </li>
        {% else %}
        <li class="nav-item{% if item.url == page.url %} active{% endif %}">
          <a class="nav-link" href="{{ item.url | relative_url }}">{{ item.title }}</a>
        </li>
        {% endif %}
        {% endfor %}
      </ul>
      <a class="btn btn-outline-light mt-3 mt-lg-0 ml-0 ml-lg-3" href="{{ site.data.nav.login.url | relative_url }}">{{ site.data.nav.login.title }}</a>
    </div>
  </div>
</nav>