Default theme implementation for printed version of book outline.
Available variables:
template_preprocess_book_export_html()
© 2001–2016 by the original authors
Licensed under the GNU General Public License, version 2 and later.
Drupal is a registered trademark of Dries Buytaert.
https://api.drupal.org/api/drupal/core!modules!book!templates!book-export-html.html.twig/8.1.x