<nav class=“site-nav”>

{%- assign default_paths = site.pages | map: "path" -%}
{%- assign page_paths = site.header_pages | default: default_paths -%}

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

</nav>