{# Every page in this app extends this file, and this file extends whatever the
   host has said should wrap it:

     a site's own templates/pdf/base.html   shadows this file entirely
     podpack                                   "base.html" -- the site's chrome
     plain Flask                               pdf/standalone.html, shipped here

   The name arrives as `pdf_layout` from a context processor on the blueprint.
   Jinja resolves `{% extends %}` against a variable perfectly well, but cannot
   be handed a list of candidates to try -- `extends` compiles to
   `environment.get_template`, not `get_or_select_template` -- so the choice is
   made in Python, where it is also inspectable as the config key
   PODPACK_PDF_BASE_TEMPLATE rather than being buried in a template.

   Child templates may fill `content` and `title`, which both known layouts
   define. A block no ancestor renders is dropped silently, so anything else is
   layout-specific and will vanish without warning on the other one. #}
{% extends pdf_layout %}