diff --git a/core/modules/system/templates/install-page.html.twig b/core/modules/system/templates/install-page.html.twig
index 24d17fa..475042e 100644
--- a/core/modules/system/templates/install-page.html.twig
+++ b/core/modules/system/templates/install-page.html.twig
@@ -11,16 +11,16 @@
  * @ingroup themeable
  */
 #}
-  <div class="layout-container">
+  <div>
 
     <header role="banner">
       {% if site_name or site_slogan %}
-        <div class="name-and-slogan">
+        <div>
           {% if site_name %}
             <h1>{{ site_name }}</h1>
           {% endif %}
           {% if site_slogan %}
-            <div class="site-slogan">{{ site_slogan }}</div>
+            <div>{{ site_slogan }}</div>
           {% endif %}
         </div>{# /.name-and-slogan #}
       {% endif %}
@@ -35,13 +35,13 @@
     </main>
 
     {% if page.sidebar_first %}
-      <aside class="layout-sidebar-first" role="complementary">
+      <aside role="complementary">
         {{ page.sidebar_first }}
       </aside>{# /.layout-sidebar-first #}
     {% endif %}
 
     {% if page.sidebar_second %}
-      <aside class="layout-sidebar-second" role="complementary">
+      <aside role="complementary">
         {{ page.sidebar_second }}
       </aside>{# /.layout-sidebar-second #}
     {% endif %}
diff --git a/core/modules/system/templates/item-list.html.twig b/core/modules/system/templates/item-list.html.twig
index bd71e7f..fdb151e 100644
--- a/core/modules/system/templates/item-list.html.twig
+++ b/core/modules/system/templates/item-list.html.twig
@@ -19,7 +19,7 @@
  */
 #}
 {%- if items or empty -%}
-  <div class="item-list">
+  <div>
     {%- if title is not empty -%}
       <h3>{{ title }}</h3>
     {%- endif -%}
diff --git a/core/modules/system/templates/links.html.twig b/core/modules/system/templates/links.html.twig
index 56c7ec2..132cef2 100644
--- a/core/modules/system/templates/links.html.twig
+++ b/core/modules/system/templates/links.html.twig
@@ -46,7 +46,7 @@
   {%- endif -%}
   <ul{{ attributes }}>
     {%- for key, item in links -%}
-      <li{{ item.attributes.addClass(key|clean_class) }}>
+      <li{{ item.attributes }}>
         {%- if item.link -%}
           {{ item.link }}
         {%- elseif item.text_attributes -%}
diff --git a/core/modules/system/templates/maintenance-page.html.twig b/core/modules/system/templates/maintenance-page.html.twig
index fd780d4..ccca6a2 100644
--- a/core/modules/system/templates/maintenance-page.html.twig
+++ b/core/modules/system/templates/maintenance-page.html.twig
@@ -21,15 +21,15 @@
     {% endif %}
 
     {% if site_name or site_slogan %}
-      <div class="name-and-slogan">
+      <div>
         {% if site_name %}
-         <h1 class="site-name">
+         <h1>
            <a href="{{ front_page }}" title="{{ 'Home'|t }}" rel="home">{{ site_name }}</a>
          </h1>
         {% endif %}
 
         {% if site_slogan %}
-          <div class="site-slogan">{{ site_slogan }}</div>
+          <div>{{ site_slogan }}</div>
         {% endif %}
       </div>{# /.name-and-slogan #}
     {% endif %}
@@ -47,13 +47,13 @@
   </main>
 
   {% if page.sidebar_first %}
-    <aside class="layout-sidebar-first" role="complementary">
+    <aside role="complementary">
       {{ page.sidebar_first }}
     </aside>{# /.layout-sidebar-first #}
   {% endif %}
 
   {% if page.sidebar_second %}
-    <aside class="layout-sidebar-second" role="complementary">
+    <aside role="complementary">
       {{ page.sidebar_second }}
     </aside>{# /.layout-sidebar-second #}
   {% endif %}
diff --git a/core/modules/system/templates/mark.html.twig b/core/modules/system/templates/mark.html.twig
index 2798bb0..1697de3 100644
--- a/core/modules/system/templates/mark.html.twig
+++ b/core/modules/system/templates/mark.html.twig
@@ -15,8 +15,8 @@
 #}
 {% if logged_in %}
   {% if status is constant('MARK_NEW') %}
-    <span class="marker">{{ 'new'|t }}</span>
+    <span>{{ 'new'|t }}</span>
   {% elseif status is constant('MARK_UPDATED') %}
-    <span class="marker">{{ 'updated'|t }}</span>
+    <span>{{ 'updated'|t }}</span>
   {% endif %}
 {% endif %}
diff --git a/core/themes/classy/templates/install-page.html.twig b/core/themes/classy/templates/install-page.html.twig
new file mode 100644
index 0000000..24d17fa
--- /dev/null
+++ b/core/themes/classy/templates/install-page.html.twig
@@ -0,0 +1,55 @@
+{#
+/**
+ * @file
+ * Default theme implementation to display a Drupal installation page.
+ *
+ * All available variables are mirrored in page.html.twig.
+ * Some may be blank but they are provided for consistency.
+ *
+ * @see template_preprocess_install_page()
+ *
+ * @ingroup themeable
+ */
+#}
+  <div class="layout-container">
+
+    <header role="banner">
+      {% if site_name or site_slogan %}
+        <div class="name-and-slogan">
+          {% if site_name %}
+            <h1>{{ site_name }}</h1>
+          {% endif %}
+          {% if site_slogan %}
+            <div class="site-slogan">{{ site_slogan }}</div>
+          {% endif %}
+        </div>{# /.name-and-slogan #}
+      {% endif %}
+    </header>
+
+    <main role="main">
+      {% if title %}
+        <h1>{{ title }}</h1>
+      {% endif %}
+      {{ messages }}
+      {{ page.content }}
+    </main>
+
+    {% if page.sidebar_first %}
+      <aside class="layout-sidebar-first" role="complementary">
+        {{ page.sidebar_first }}
+      </aside>{# /.layout-sidebar-first #}
+    {% endif %}
+
+    {% if page.sidebar_second %}
+      <aside class="layout-sidebar-second" role="complementary">
+        {{ page.sidebar_second }}
+      </aside>{# /.layout-sidebar-second #}
+    {% endif %}
+
+    {% if page.footer %}
+      <footer role="contentinfo">
+        {{ page.footer }}
+      </footer>
+    {% endif %}
+
+  </div>{# /.layout-container #}
diff --git a/core/themes/classy/templates/item-list.html.twig b/core/themes/classy/templates/item-list.html.twig
new file mode 100644
index 0000000..bd71e7f
--- /dev/null
+++ b/core/themes/classy/templates/item-list.html.twig
@@ -0,0 +1,36 @@
+{#
+/**
+ * @file
+ * Default theme implementation for an item list.
+ *
+ * Available variables:
+ * - items: A list of items. Each item contains:
+ *   - attributes: HTML attributes to be applied to each list item.
+ *   - value: The content of the list element.
+ * - title: The title of the list.
+ * - list_type: The tag for list element ("ul" or "ol").
+ * - attributes: HTML attributes to be applied to the list.
+ * - empty: A message to display when there are no items. Allowed value is a
+ *   string or render array.
+ *
+ * @see template_preprocess_item_list()
+ *
+ * @ingroup themeable
+ */
+#}
+{%- if items or empty -%}
+  <div class="item-list">
+    {%- if title is not empty -%}
+      <h3>{{ title }}</h3>
+    {%- endif -%}
+    {%- if items -%}
+      <{{ list_type }}{{ attributes }}>
+        {%- for item in items -%}
+          <li{{ item.attributes }}>{{ item.value }}</li>
+        {%- endfor -%}
+      </{{ list_type }}>
+    {%- else -%}
+      {{- empty -}}
+    {%- endif -%}
+  </div>
+{%- endif %}
diff --git a/core/themes/classy/templates/links.html.twig b/core/themes/classy/templates/links.html.twig
new file mode 100644
index 0000000..56c7ec2
--- /dev/null
+++ b/core/themes/classy/templates/links.html.twig
@@ -0,0 +1,60 @@
+{#
+/**
+ * @file
+ * Default theme implementation for a set of links.
+ *
+ * Available variables:
+ * - attributes: Attributes for the UL containing the list of links.
+ * - links: Links to be output.
+ *   Each link will have the following elements:
+ *   - title: The link text.
+ *   - href: The link URL. If omitted, the 'title' is shown as a plain text
+ *     item in the links list. If 'href' is supplied, the entire link is passed
+ *     to l() as its $options parameter.
+ *   - html: (optional) Whether or not 'title' is HTML. If set, the title will
+ *     not be passed through \Drupal\Component\Utility\String::checkPlain().
+ *   - attributes: (optional) HTML attributes for the anchor, or for the <span>
+ *     tag if no 'href' is supplied.
+ *   - link_key: The link CSS class.
+ * - heading: (optional) A heading to precede the links.
+ *   - text: The heading text.
+ *   - level: The heading level (e.g. 'h2', 'h3').
+ *   - attributes: (optional) A keyed list of attributes for the heading.
+ *   If the heading is a string, it will be used as the text of the heading and
+ *   the level will default to 'h2'.
+ *
+ *   Headings should be used on navigation menus and any list of links that
+ *   consistently appears on multiple pages. To make the heading invisible use
+ *   the 'visually-hidden' CSS class. Do not use 'display:none', which
+ *   removes it from screen readers and assistive technology. Headings allow
+ *   screen reader and keyboard only users to navigate to or skip the links.
+ *   See http://juicystudio.com/article/screen-readers-display-none.php and
+ *   http://www.w3.org/TR/WCAG-TECHS/H42.html for more information.
+ *
+ * @see template_preprocess_links()
+ *
+ * @ingroup themeable
+ */
+#}
+{% if links -%}
+  {%- if heading -%}
+    {%- if heading.level -%}
+      <{{ heading.level }}{{ heading.attributes }}>{{ heading.text }}</{{ heading.level }}>
+    {%- else -%}
+      <h2{{ heading.attributes }}>{{ heading.text }}</h2>
+    {%- endif -%}
+  {%- endif -%}
+  <ul{{ attributes }}>
+    {%- for key, item in links -%}
+      <li{{ item.attributes.addClass(key|clean_class) }}>
+        {%- if item.link -%}
+          {{ item.link }}
+        {%- elseif item.text_attributes -%}
+          <span{{ item.text_attributes }}>{{ item.text }}</span>
+        {%- else -%}
+          {{ item.text }}
+        {%- endif -%}
+      </li>
+    {%- endfor -%}
+  </ul>
+{%- endif %}
diff --git a/core/themes/classy/templates/maintenance-page.html.twig b/core/themes/classy/templates/maintenance-page.html.twig
new file mode 100644
index 0000000..fd780d4
--- /dev/null
+++ b/core/themes/classy/templates/maintenance-page.html.twig
@@ -0,0 +1,67 @@
+{#
+/**
+ * @file
+ * Default theme implementation to display a single Drupal page while offline.
+ *
+ * All available variables are mirrored in page.html.twig.
+ * Some may be blank but they are provided for consistency.
+ *
+ * @see template_preprocess_maintenance_page()
+ *
+ * @ingroup themeable
+ */
+#}
+<div class="layout-container">
+
+  <header role="banner">
+    {% if logo %}
+      <a href="{{ front_page }}" title="{{ 'Home'|t }}" rel="home">
+        <img src="{{ logo }}" alt="{{ 'Home'|t }}"/>
+      </a>
+    {% endif %}
+
+    {% if site_name or site_slogan %}
+      <div class="name-and-slogan">
+        {% if site_name %}
+         <h1 class="site-name">
+           <a href="{{ front_page }}" title="{{ 'Home'|t }}" rel="home">{{ site_name }}</a>
+         </h1>
+        {% endif %}
+
+        {% if site_slogan %}
+          <div class="site-slogan">{{ site_slogan }}</div>
+        {% endif %}
+      </div>{# /.name-and-slogan #}
+    {% endif %}
+
+  </header>
+
+  <main role="main">
+    {% if title %}
+      <h1>{{ title }}</h1>
+    {% endif %}
+
+    {{ messages }}
+
+    {{ page.content }}
+  </main>
+
+  {% if page.sidebar_first %}
+    <aside class="layout-sidebar-first" role="complementary">
+      {{ page.sidebar_first }}
+    </aside>{# /.layout-sidebar-first #}
+  {% endif %}
+
+  {% if page.sidebar_second %}
+    <aside class="layout-sidebar-second" role="complementary">
+      {{ page.sidebar_second }}
+    </aside>{# /.layout-sidebar-second #}
+  {% endif %}
+
+  {% if page.footer %}
+    <footer role="contentinfo">
+      {{ page.footer }}
+    </footer>
+  {% endif %}
+
+</div>{# /.layout-container #}
diff --git a/core/themes/classy/templates/mark.html.twig b/core/themes/classy/templates/mark.html.twig
new file mode 100644
index 0000000..2798bb0
--- /dev/null
+++ b/core/themes/classy/templates/mark.html.twig
@@ -0,0 +1,22 @@
+{#
+/**
+ * @file
+ * Default theme implementation for a marker for new or updated content.
+ *
+ * Available variables:
+ * - status: Number representing the marker status to display. Use the constants
+ *   below for comparison:
+ *   - MARK_NEW
+ *   - MARK_UPDATED
+ *   - MARK_READ
+ *
+ * @ingroup themeable
+ */
+#}
+{% if logged_in %}
+  {% if status is constant('MARK_NEW') %}
+    <span class="marker">{{ 'new'|t }}</span>
+  {% elseif status is constant('MARK_UPDATED') %}
+    <span class="marker">{{ 'updated'|t }}</span>
+  {% endif %}
+{% endif %}
diff --git a/core/themes/classy/templates/menu-local-action.html.twig b/core/themes/classy/templates/menu-local-action.html.twig
new file mode 100644
index 0000000..0eb03a9
--- /dev/null
+++ b/core/themes/classy/templates/menu-local-action.html.twig
@@ -0,0 +1,15 @@
+{#
+/**
+ * @file
+ * Default theme implementation for a single local action link.
+ *
+ * Available variables:
+ * - attributes: HTML attributes for the wrapper element.
+ * - link: A rendered link element.
+ *
+ * @see template_preprocess_menu_local_action()
+ *
+ * @ingroup themeable
+ */
+#}
+<li{{ attributes }}>{{ link }}</li>