diff --git a/core/modules/book/templates/book-all-books-block.html.twig b/core/modules/book/templates/book-all-books-block.html.twig
index 61609826f9a2e768ec18059a5322a74e0864f9d0..a4d0c9ad820d5a404788a5481a14625094b8f09c 100644
--- a/core/modules/book/templates/book-all-books-block.html.twig
+++ b/core/modules/book/templates/book-all-books-block.html.twig
@@ -18,7 +18,7 @@
  */
 #}
 {% for book in book_menus %}
-  <nav id="book-block-menu-{{ book.id }}" class="book-block-menu" role="navigation" aria-label="{% trans %}Book outline for {{ book.title }}{% endtrans %}">
+  <nav role="navigation" aria-label="{% trans %}Book outline for {{ book.title }}{% endtrans %}">
     {{ book.menu }}
   </nav>
 {% endfor %}
diff --git a/core/modules/book/templates/book-export-html.html.twig b/core/modules/book/templates/book-export-html.html.twig
index cbeb3b3797ea9ff24fee5100fe463a292a1808e5..5fb2e971a53a545c95df7b417f5d0f74ea8004d4 100644
--- a/core/modules/book/templates/book-export-html.html.twig
+++ b/core/modules/book/templates/book-export-html.html.twig
@@ -37,7 +37,7 @@
     #}
 
   {% for i in 1..depth-1 if depth > 1 %}
-    <div class="section-{{ i }}">
+    <div>
   {% endfor %}
   {{ contents }}
   {% for i in 1..depth-1 if depth > 1 %}
diff --git a/core/modules/book/templates/book-navigation.html.twig b/core/modules/book/templates/book-navigation.html.twig
index abb0d314fd7d21878d568b1a04c3aa196a75c55e..f10a4e5f65783d7993a6d38f9a5876828c93081c 100644
--- a/core/modules/book/templates/book-navigation.html.twig
+++ b/core/modules/book/templates/book-navigation.html.twig
@@ -31,23 +31,23 @@
  */
 #}
 {% if tree or has_links %}
-  <nav id="book-navigation-{{ book_id }}" class="book-navigation" role="navigation" aria-labelledby="book-label-{{ book_id }}">
+  <nav id="book-navigation-{{ book_id }}" role="navigation" aria-labelledby="book-label-{{ book_id }}">
     {{ tree }}
     {% if has_links %}
-      <h2 class="visually-hidden" id="book-label-{{ book_id }}">{{ 'Book traversal links for'|t }} {{ book_title }}</h2>
-      <ul class="book-pager">
+      <h2>{{ 'Book traversal links for'|t }} {{ book_title }}</h2>
+      <ul>
       {% if prev_url %}
-        <li class="previous">
+        <li>
           <a href="{{ prev_url }}" rel="prev" title="{{ 'Go to previous page'|t }}"><b>{{ '‹'|t }}</b> {{ prev_title }}</a>
         </li>
       {% endif %}
       {% if parent_url %}
-        <li class="up">
+        <li>
           <a href="{{ parent_url }}" title="{{ 'Go to parent page'|t }}">{{ 'Up'|t }}</a>
         </li>
       {% endif %}
       {% if next_url %}
-        <li class="next">
+        <li>
           <a href="{{ next_url }}" rel="next" title="{{ 'Go to next page'|t }}">{{ next_title }} <b>{{ '›'|t }}</b></a>
         </li>
       {% endif %}
diff --git a/core/modules/book/templates/book-node-export-html.html.twig b/core/modules/book/templates/book-node-export-html.html.twig
index 0efa9a7adcf405a383752334a5fce30bde0f3616..39a41fcee0e497600b8e550557c3376b34ae9b95 100644
--- a/core/modules/book/templates/book-node-export-html.html.twig
+++ b/core/modules/book/templates/book-node-export-html.html.twig
@@ -15,8 +15,8 @@
  * @ingroup themeable
  */
 #}
-<article id="node-{{ node.id }}" class="section-{{ depth }}">
-  <h1 class="book-heading">{{ title }}</h1>
+<article>
+  <h1>{{ title }}</h1>
   {{ content }}
   {{ children }}
 </article>
diff --git a/core/modules/book/templates/book-tree.html.twig b/core/modules/book/templates/book-tree.html.twig
index 9f640d0b4cfb22600aa3d0b09677ce9f5666e8a5..46068c7481e56cdf485022426f52fb1f6910e138 100644
--- a/core/modules/book/templates/book-tree.html.twig
+++ b/core/modules/book/templates/book-tree.html.twig
@@ -13,4 +13,4 @@
  * @ingroup themeable
  */
 #}
-<ul class="menu">{{ tree }}</ul>
+<ul>{{ tree }}</ul>
diff --git a/core/themes/classy/templates/book-all-books-block.html.twig b/core/themes/classy/templates/book-all-books-block.html.twig
new file mode 100644
index 0000000000000000000000000000000000000000..61609826f9a2e768ec18059a5322a74e0864f9d0
--- /dev/null
+++ b/core/themes/classy/templates/book-all-books-block.html.twig
@@ -0,0 +1,24 @@
+{#
+/**
+ * @file
+ * Default theme implementation for rendering book outlines within a block.
+ *
+ * This template is used only when the block is configured to "show block on all
+ * pages", which presents multiple independent books on all pages.
+ *
+ * Available variables:
+ * - book_menus: Book outlines.
+ *   - id: The parent book ID.
+ *   - title: The parent book title.
+ *   - menu: The top-level book links.
+ *
+ * @see template_preprocess_book_all_books_block()
+ *
+ * @ingroup themeable
+ */
+#}
+{% for book in book_menus %}
+  <nav id="book-block-menu-{{ book.id }}" class="book-block-menu" role="navigation" aria-label="{% trans %}Book outline for {{ book.title }}{% endtrans %}">
+    {{ book.menu }}
+  </nav>
+{% endfor %}
diff --git a/core/themes/classy/templates/book-export-html.html.twig b/core/themes/classy/templates/book-export-html.html.twig
new file mode 100644
index 0000000000000000000000000000000000000000..cbeb3b3797ea9ff24fee5100fe463a292a1808e5
--- /dev/null
+++ b/core/themes/classy/templates/book-export-html.html.twig
@@ -0,0 +1,47 @@
+{#
+/**
+ * @file
+ * Default theme implementation for printed version of book outline.
+ *
+ * Available variables:
+ * - title: Top level node title.
+ * - head: Header tags.
+ * - language: Language object.
+ * - language_rtl: A flag indicating whether the current display language is a
+ *   right to left language.
+ * - base_url: URL to the home page.
+ * - contents: Nodes within the current outline rendered through
+ *   book-node-export-html.html.twig.
+ *
+ * @see template_preprocess_book_export_html()
+ *
+ * @ingroup themeable
+ */
+#}
+<!DOCTYPE html>
+<html{{ html_attributes }}>
+  <head>
+    <title>{{ title }}</title>
+    {{ page.head }}
+    <base href="{{ base_url }}" />
+    <link type="text/css" rel="stylesheet" href="misc/print.css" />
+  </head>
+  <body>
+    {#
+      The given node is embedded to its absolute depth in a top level section.
+      For example, a child node with depth 2 in the hierarchy is contained in
+      (otherwise empty) div elements corresponding to depth 0 and depth 1. This
+      is intended to support WYSIWYG output - e.g., level 3 sections always look
+      like level 3 sections, no matter their depth relative to the node selected
+      to be exported as printer-friendly HTML.
+    #}
+
+  {% for i in 1..depth-1 if depth > 1 %}
+    <div class="section-{{ i }}">
+  {% endfor %}
+  {{ contents }}
+  {% for i in 1..depth-1 if depth > 1 %}
+    </div>
+  {% endfor %}
+  </body>
+</html>
diff --git a/core/themes/classy/templates/book-navigation.html.twig b/core/themes/classy/templates/book-navigation.html.twig
new file mode 100644
index 0000000000000000000000000000000000000000..abb0d314fd7d21878d568b1a04c3aa196a75c55e
--- /dev/null
+++ b/core/themes/classy/templates/book-navigation.html.twig
@@ -0,0 +1,57 @@
+{#
+/**
+ * @file
+ * Default theme implementation to navigate books.
+ *
+ * Presented under nodes that are a part of book outlines.
+ *
+ * Available variables:
+ * - tree: The immediate children of the current node rendered as an unordered
+ *   list.
+ * - current_depth: Depth of the current node within the book outline. Provided
+ *   for context.
+ * - prev_url: URL to the previous node.
+ * - prev_title: Title of the previous node.
+ * - parent_url: URL to the parent node.
+ * - parent_title: Title of the parent node. Not printed by default. Provided
+ *   as an option.
+ * - next_url: URL to the next node.
+ * - next_title: Title of the next node.
+ * - has_links: Flags TRUE whenever the previous, parent or next data has a
+ *   value.
+ * - book_id: The book ID of the current outline being viewed. Same as the node
+ *   ID containing the entire outline. Provided for context.
+ * - book_url: The book/node URL of the current outline being viewed. Provided
+ *   as an option. Not used by default.
+ * - book_title: The book/node title of the current outline being viewed.
+ *
+ * @see template_preprocess_book_navigation()
+ *
+ * @ingroup themeable
+ */
+#}
+{% if tree or has_links %}
+  <nav id="book-navigation-{{ book_id }}" class="book-navigation" role="navigation" aria-labelledby="book-label-{{ book_id }}">
+    {{ tree }}
+    {% if has_links %}
+      <h2 class="visually-hidden" id="book-label-{{ book_id }}">{{ 'Book traversal links for'|t }} {{ book_title }}</h2>
+      <ul class="book-pager">
+      {% if prev_url %}
+        <li class="previous">
+          <a href="{{ prev_url }}" rel="prev" title="{{ 'Go to previous page'|t }}"><b>{{ '‹'|t }}</b> {{ prev_title }}</a>
+        </li>
+      {% endif %}
+      {% if parent_url %}
+        <li class="up">
+          <a href="{{ parent_url }}" title="{{ 'Go to parent page'|t }}">{{ 'Up'|t }}</a>
+        </li>
+      {% endif %}
+      {% if next_url %}
+        <li class="next">
+          <a href="{{ next_url }}" rel="next" title="{{ 'Go to next page'|t }}">{{ next_title }} <b>{{ '›'|t }}</b></a>
+        </li>
+      {% endif %}
+    </ul>
+    {% endif %}
+  </nav>
+{% endif %}
diff --git a/core/themes/classy/templates/book-node-export-html.html.twig b/core/themes/classy/templates/book-node-export-html.html.twig
new file mode 100644
index 0000000000000000000000000000000000000000..0efa9a7adcf405a383752334a5fce30bde0f3616
--- /dev/null
+++ b/core/themes/classy/templates/book-node-export-html.html.twig
@@ -0,0 +1,22 @@
+{#
+/**
+ * @file
+ * Default theme implementation for a single node in a printer-friendly outline.
+ *
+ * Available variables:
+ * - node: Fully loaded node.
+ * - depth: Depth of the current node inside the outline.
+ * - title: Node title.
+ * - content: Node content.
+ * - children: All the child nodes recursively rendered through this file.
+ *
+ * @see template_preprocess_book_node_export_html()
+ *
+ * @ingroup themeable
+ */
+#}
+<article id="node-{{ node.id }}" class="section-{{ depth }}">
+  <h1 class="book-heading">{{ title }}</h1>
+  {{ content }}
+  {{ children }}
+</article>
diff --git a/core/themes/classy/templates/book-tree.html.twig b/core/themes/classy/templates/book-tree.html.twig
new file mode 100644
index 0000000000000000000000000000000000000000..9f640d0b4cfb22600aa3d0b09677ce9f5666e8a5
--- /dev/null
+++ b/core/themes/classy/templates/book-tree.html.twig
@@ -0,0 +1,16 @@
+{#
+/**
+ * @file
+ * Default theme implementation for a book tree.
+ *
+ * Returns HTML for a wrapper for a book sub-tree.
+ *
+ * Available variables:
+ *   - tree: An HTML string containing the tree's items.
+ *
+ * @see template_preprocess_book_tree()
+ *
+ * @ingroup themeable
+ */
+#}
+<ul class="menu">{{ tree }}</ul>