diff --git a/core/modules/system/templates/block--system-branding-block.html.twig b/core/modules/system/templates/block--system-branding-block.html.twig
index f648773..4c64251 100644
--- a/core/modules/system/templates/block--system-branding-block.html.twig
+++ b/core/modules/system/templates/block--system-branding-block.html.twig
@@ -17,16 +17,16 @@
 #}
 {% block content %}
   {% if site_logo %}
-    <a href="{{ url('<front>') }}" title="{{ 'Home'|t }}" rel="home" class="site-logo">
+    <a href="{{ url('<front>') }}" title="{{ 'Home'|t }}" rel="home">
       <img src="{{ site_logo }}" alt="{{ 'Home'|t }}" />
     </a>
   {% endif %}
   {% if site_name %}
-    <div class="site-name">
+    <div>
       <a href="{{ url('<front>') }}" title="{{ 'Home'|t }}" rel="home">{{ site_name }}</a>
     </div>
   {% endif %}
   {% if site_slogan %}
-    <div class="site-slogan">{{ site_slogan }}</div>
+    <div>{{ site_slogan }}</div>
   {% endif %}
 {% endblock %}
diff --git a/core/modules/system/templates/block--system-menu-block.html.twig b/core/modules/system/templates/block--system-menu-block.html.twig
index dff7e39..4328747 100644
--- a/core/modules/system/templates/block--system-menu-block.html.twig
+++ b/core/modules/system/templates/block--system-menu-block.html.twig
@@ -40,22 +40,14 @@
  * @ingroup themeable
  */
 #}
-{%
-  set classes = [
-    'block',
-    'block-menu',
-    'navigation',
-    'menu--' ~ derivative_plugin_id|clean_class,
-  ]
-%}
 {% set heading_id = attributes.id ~ '-menu'|clean_id %}
-<nav{{ attributes.addClass(classes) }} role="navigation" aria-labelledby="{{ heading_id }}">
+<nav{{ attributes }} role="navigation" aria-labelledby="{{ heading_id }}">
   {# Label. If not displayed, we still provide it for screen readers. #}
   {% if not configuration.label_display %}
     {% set title_attributes = title_attributes.addClass('visually-hidden') %}
   {% endif %}
   {{ title_prefix }}
-  <h2 id="{{ heading_id }}"{{ title_attributes }}>{{ configuration.label }}</h2>
+  <h2{{ title_attributes }}>{{ configuration.label }}</h2>
   {{ title_suffix }}
 
   {# Menu. #}
diff --git a/core/modules/system/templates/breadcrumb.html.twig b/core/modules/system/templates/breadcrumb.html.twig
index f6a1705..91d8376 100644
--- a/core/modules/system/templates/breadcrumb.html.twig
+++ b/core/modules/system/templates/breadcrumb.html.twig
@@ -10,8 +10,8 @@
  */
 #}
 {% if breadcrumb %}
-  <nav class="breadcrumb" role="navigation" aria-labelledby="system-breadcrumb">
-    <h2 id="system-breadcrumb" class="visually-hidden">{{ 'Breadcrumb'|t }}</h2>
+  <nav role="navigation" aria-labelledby="system-breadcrumb">
+    <h2 class="visually-hidden">{{ 'Breadcrumb'|t }}</h2>
     <ol>
     {% for item in breadcrumb %}
       <li>
diff --git a/core/themes/classy/templates/block--system-branding-block.html.twig b/core/themes/classy/templates/block--system-branding-block.html.twig
new file mode 100644
index 0000000..f648773
--- /dev/null
+++ b/core/themes/classy/templates/block--system-branding-block.html.twig
@@ -0,0 +1,32 @@
+{% extends "block.html.twig" %}
+{#
+/**
+ * @file
+ * Default theme implementation for a branding block.
+ *
+ * Each branding element variable (logo, name, slogan) is only available if
+ * enabled in the block configuration.
+ *
+ * Available variables:
+ * - site_logo: Logo for site as defined in Appearance or theme settings.
+ * - site_name: Name for site as defined in Site information settings.
+ * - site_slogan: Slogan for site as defined in Site information settings.
+ *
+ * @ingroup themeable
+ */
+#}
+{% block content %}
+  {% if site_logo %}
+    <a href="{{ url('<front>') }}" title="{{ 'Home'|t }}" rel="home" class="site-logo">
+      <img src="{{ site_logo }}" alt="{{ 'Home'|t }}" />
+    </a>
+  {% endif %}
+  {% if site_name %}
+    <div class="site-name">
+      <a href="{{ url('<front>') }}" title="{{ 'Home'|t }}" rel="home">{{ site_name }}</a>
+    </div>
+  {% endif %}
+  {% if site_slogan %}
+    <div class="site-slogan">{{ site_slogan }}</div>
+  {% endif %}
+{% endblock %}
diff --git a/core/themes/classy/templates/block--system-menu-block.html.twig b/core/themes/classy/templates/block--system-menu-block.html.twig
new file mode 100644
index 0000000..dff7e39
--- /dev/null
+++ b/core/themes/classy/templates/block--system-menu-block.html.twig
@@ -0,0 +1,65 @@
+{#
+/**
+ * @file
+ * Default theme implementation for a menu block.
+ *
+ * Available variables:
+ * - plugin_id: The ID of the block implementation.
+ * - label: The configured label of the block if visible.
+ * - configuration: A list of the block's configuration values.
+ *   - label: The configured label for the block.
+ *   - label_display: The display settings for the label.
+ *   - module: The module that provided this block plugin.
+ *   - cache: The cache settings.
+ *   - Block plugin specific settings will also be stored here.
+ * - block - The full block entity.
+ *   - label_hidden: The hidden block title value if the block was
+ *     configured to hide the title ('label' is empty in this case).
+ *   - module: The module that generated the block.
+ *   - delta: An ID for the block, unique within each module.
+ *   - region: The block region embedding the current block.
+ * - content: The content of this block.
+ * - attributes: HTML attributes for the containing element.
+ *   - id: A valid HTML ID and guaranteed unique.
+ * - title_attributes: HTML attributes for the title element.
+ * - content_attributes: HTML attributes for the content element.
+ * - title_prefix: Additional output populated by modules, intended to be
+ *   displayed in front of the main title tag that appears in the template.
+ * - title_suffix: Additional output populated by modules, intended to be
+ *   displayed after the main title tag that appears in the template.
+ *
+ * Headings should be used on navigation menus that consistently appear on
+ * multiple pages. When this menu block's label is configured to not be
+ * displayed, it is automatically made invisible using the 'visually-hidden' CSS
+ * class, which still keeps it visible for 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.
+ *
+ * @ingroup themeable
+ */
+#}
+{%
+  set classes = [
+    'block',
+    'block-menu',
+    'navigation',
+    'menu--' ~ derivative_plugin_id|clean_class,
+  ]
+%}
+{% set heading_id = attributes.id ~ '-menu'|clean_id %}
+<nav{{ attributes.addClass(classes) }} role="navigation" aria-labelledby="{{ heading_id }}">
+  {# Label. If not displayed, we still provide it for screen readers. #}
+  {% if not configuration.label_display %}
+    {% set title_attributes = title_attributes.addClass('visually-hidden') %}
+  {% endif %}
+  {{ title_prefix }}
+  <h2 id="{{ heading_id }}"{{ title_attributes }}>{{ configuration.label }}</h2>
+  {{ title_suffix }}
+
+  {# Menu. #}
+  {% block content %}
+    {{ content }}
+  {% endblock %}
+</nav>
diff --git a/core/themes/classy/templates/breadcrumb.html.twig b/core/themes/classy/templates/breadcrumb.html.twig
new file mode 100644
index 0000000..f6a1705
--- /dev/null
+++ b/core/themes/classy/templates/breadcrumb.html.twig
@@ -0,0 +1,27 @@
+{#
+/**
+ * @file
+ * Default theme implementation for a breadcrumb trail.
+ *
+ * Available variables:
+ * - breadcrumb: Breadcrumb trail items.
+ *
+ * @ingroup themeable
+ */
+#}
+{% if breadcrumb %}
+  <nav class="breadcrumb" role="navigation" aria-labelledby="system-breadcrumb">
+    <h2 id="system-breadcrumb" class="visually-hidden">{{ 'Breadcrumb'|t }}</h2>
+    <ol>
+    {% for item in breadcrumb %}
+      <li>
+        {% if item.url %}
+          <a href="{{ item.url }}">{{ item.text }}</a>
+        {% else %}
+          {{ item.text }}
+        {% endif %}
+      </li>
+    {% endfor %}
+    </ol>
+  </nav>
+{% endif %}