<header>

<div class="wrapper">
    {%- assign default_paths = site.pages | map: "path" -%}
    {%- assign page_paths = site.header_pages | default: default_paths -%}
    <h1><a href="{{ "/" | relative_url }}">{{ site.title | escape }}</a></h1>
    {%- if page_paths -%}
    <nav>
        {%- for path in page_paths -%}
            {%- assign my_page = site.pages | where: "path", path | first -%}
            {%- if my_page.title -%}
                <a href="{{ my_page.url | relative_url }}">{{ my_page.title | escape }}</a>
            {%- endif -%}
        {%- endfor -%}
    </nav>
    {%- endif -%}
</div>

</header>