{# The application's header, defined once and used by every page.

   Four templates each carried their own copy: the logo was an <h1> on three of
   them and a link on the fourth, one had a stray nested anchor, and the
   navigation had drifted so that Plugins appeared only on the dataset list.

   Pages that need more in the bar -- a breadcrumb, a toolbar -- call it and
   put that content in the body:

       {% from "partials/header.html" import header with context %}
       {% call header('explorer') %}
           <div class="header-actions">...</div>
       {% endcall %}

   Pages that need nothing extra call it plainly: {{ header('datasets') }} #}
{% macro header(active) %}
<header class="header">
    {# A link home rather than a heading: the same logo on every page is
       navigation, not the page's title. #}
    <a href="{{ base_url }}/" class="header-title">
        <img src="{{ base_url }}/static/images/metaseed-logo-light.svg" alt="Metaseed" class="header-logo">
    </a>
    <nav class="header-nav">
        {% set nav_active = active %}
        {% include "partials/global_nav.html" %}
    </nav>
    {% if caller %}{{ caller() }}{% endif %}
</header>
{% endmacro %}