header.html

<nav class="navbar navbar-expand-md navbar-dark bg-dark fixed-top">
  {% assign default_paths = site.pages | sort: "order" | map: "path" %}
  {% assign page_paths = site.header_pages | default: default_paths %}
  <a class="navbar-brand" href="{{ "/" | relative_url }}">
    <img src="/assets/images/logo.png" class="logo" style="width: 200px;"/>
  </a>


  {% if page_paths %}
    <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarsExampleDefault" aria-controls="navbarsExampleDefault" aria-expanded="false" aria-label="Toggle navigation">
      <span class="navbar-toggler-icon"></span>
    </button>
    <div class="collapse navbar-collapse" id="navbarsExampleDefault">
      <ul class="navbar-nav ml-auto">

        {% for path in page_paths %}
          {% assign my_page = site.pages | where: "path", path | first %}
          {% if my_page.title %}
          <li class="nav-item active">
            <a class="nav-link" href="{{ my_page.url | relative_url }}">{{ my_page.title | escape }}</a>
          </li>
          {% endif %}
        {% endfor %}
      </ul>
    </div>
  {% endif %}
</nav>