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 4cf0f1a..5a34b7e 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..1f8beaa 100644
--- a/core/modules/system/templates/block--system-menu-block.html.twig
+++ b/core/modules/system/templates/block--system-menu-block.html.twig
@@ -40,16 +40,8 @@
  * @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 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') %}
diff --git a/core/modules/system/templates/breadcrumb.html.twig b/core/modules/system/templates/breadcrumb.html.twig
index f6a1705..0331409 100644
--- a/core/modules/system/templates/breadcrumb.html.twig
+++ b/core/modules/system/templates/breadcrumb.html.twig
@@ -10,7 +10,7 @@
  */
 #}
 {% if breadcrumb %}
-  <nav class="breadcrumb" role="navigation" aria-labelledby="system-breadcrumb">
+  <nav role="navigation" aria-labelledby="system-breadcrumb">
     <h2 id="system-breadcrumb" class="visually-hidden">{{ 'Breadcrumb'|t }}</h2>
     <ol>
     {% for item in breadcrumb %}
diff --git a/core/modules/system/templates/block--system-branding-block.html.twig b/core/themes/classy/templates/block--system-branding-block.html.twig
similarity index 100%
copy from core/modules/system/templates/block--system-branding-block.html.twig
copy to core/themes/classy/templates/block--system-branding-block.html.twig
diff --git a/core/modules/system/templates/block--system-menu-block.html.twig b/core/themes/classy/templates/block--system-menu-block.html.twig
similarity index 100%
copy from core/modules/system/templates/block--system-menu-block.html.twig
copy to core/themes/classy/templates/block--system-menu-block.html.twig
diff --git a/core/modules/system/templates/breadcrumb.html.twig b/core/themes/classy/templates/breadcrumb.html.twig
similarity index 100%
copy from core/modules/system/templates/breadcrumb.html.twig
copy to core/themes/classy/templates/breadcrumb.html.twig