{# The application's navigation, defined once.

   Four templates each carried their own copy and all four had drifted: Plugins
   appeared only on the dataset list, Docs was missing from the builder's start
   page, and "Builder" pointed at two different routes depending on where you
   read it. A person moving between pages watched buttons come and go.

   `nav_active` names the current section: datasets, spec-builder, explorer or
   plugins. Anything else simply highlights nothing. #}
<a href="{{ base_url }}/" class="nav-btn {% if nav_active == 'datasets' %}active{% endif %}" data-testid="nav-datasets">Datasets</a>
<a href="{{ base_url }}/spec-builder" class="nav-btn {% if nav_active == 'spec-builder' %}active{% endif %}" data-testid="nav-spec-builder">Builder</a>
<a href="{{ base_url }}/explore/" class="nav-btn {% if nav_active == 'explorer' %}active{% endif %}" data-testid="nav-explorer">Explorer</a>
<a href="{{ base_url }}/settings" class="nav-btn {% if nav_active == 'plugins' %}active{% endif %}" data-testid="nav-plugins">Plugins</a>
<a href="https://sorenwacker.github.io/metaseed/" class="nav-btn" data-testid="nav-docs" target="_blank" rel="noopener">Docs</a>