diff --git a/core/modules/system/templates/page.html.twig b/core/modules/system/templates/page.html.twig
index 627d7c7..04dddca 100644
--- a/core/modules/system/templates/page.html.twig
+++ b/core/modules/system/templates/page.html.twig
@@ -59,7 +59,7 @@
  * @ingroup themeable
  */
 #}
-<div class="layout-container">
+<div>
 
   <header role="banner">
     {% if logo %}
@@ -69,21 +69,21 @@
     {% endif %}
 
     {% if site_name or site_slogan %}
-      <div class="name-and-slogan">
+      <div>
 
         {# Use h1 when the content title is empty #}
         {% if title %}
-          <strong class="site-name">
+          <strong>
             <a href="{{ front_page }}" title="{{ 'Home'|t }}" rel="home">{{ site_name }}</a>
           </strong>
         {% else %}
-          <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 %}
@@ -103,7 +103,7 @@
   <main role="main">
     <a id="main-content" tabindex="-1"></a>{# link is in html.html.twig #}
 
-    <div class="layout-content">
+    <div>
       {{ page.highlighted }}
 
       {{ title_prefix }}
@@ -115,20 +115,20 @@
       {{ tabs }}
 
       {% if action_links %}
-        <nav class="action-links">{{ action_links }}</nav>
+        <nav>{{ action_links }}</nav>
       {% endif %}
 
       {{ page.content }}
     </div>{# /.layout-content #}
 
     {% if page.sidebar_first %}
-      <aside class="layout-sidebar-first" role="complementary">
+      <aside role="complementary">
         {{ page.sidebar_first }}
       </aside>
     {% endif %}
 
     {% if page.sidebar_second %}
-      <aside class="layout-sidebar-second" role="complementary">
+      <aside role="complementary">
         {{ page.sidebar_second }}
       </aside>
     {% endif %}
diff --git a/core/modules/system/templates/pager.html.twig b/core/modules/system/templates/pager.html.twig
index a7acd5e..7540fb4 100644
--- a/core/modules/system/templates/pager.html.twig
+++ b/core/modules/system/templates/pager.html.twig
@@ -32,12 +32,12 @@
  */
 #}
 {% if items %}
-  <nav class="pager" role="navigation" aria-labelledby="pagination-heading">
-    <h4 id="pagination-heading" class="visually-hidden">{{ 'Pagination'|t }}</h4>
-    <ul class="pager__items">
+  <nav role="navigation" aria-labelledby="pagination-heading">
+    <h4 class="visually-hidden">{{ 'Pagination'|t }}</h4>
+    <ul>
       {# Print first item if we are not on the first page. #}
       {% if items.first %}
-        <li class="pager__item pager__item--first">
+        <li>
           <a href="{{ items.first.href }}" title="{{ 'Go to first page'|t }}"{{ items.first.attributes }}>
             <span class="visually-hidden">{{ 'First page'|t }}</span>
             <span aria-hidden="true">{{ items.first.text|default('« first'|t) }}</span>
@@ -46,7 +46,7 @@
       {% endif %}
       {# Print previous item if we are not on the first page. #}
       {% if items.previous %}
-        <li class="pager__item pager__item--previous">
+        <li>
           <a href="{{ items.previous.href }}" title="{{ 'Go to previous page'|t }}" rel="prev"{{ items.previous.attributes }}>
             <span class="visually-hidden">{{ 'Previous page'|t }}</span>
             <span aria-hidden="true">{{ items.previous.text|default('‹ previous'|t) }}</span>
@@ -55,11 +55,11 @@
       {% endif %}
       {# Add an ellipsis if there are further previous pages. #}
       {% if ellipses.previous %}
-        <li class="pager__item pager__item--ellipsis" role="presentation">&hellip;</li>
+        <li role="presentation">&hellip;</li>
       {% endif %}
       {# Now generate the actual pager piece. #}
       {% for key, item in items.pages %}
-        <li class="pager__item{{ current == key ? ' is-active' : '' }}">
+        <li>
           {% if current == key %}
             {% set title = 'Current page'|t %}
           {% else %}
@@ -75,11 +75,11 @@
       {% endfor %}
       {# Add an ellipsis if there are further next pages. #}
       {% if ellipses.next %}
-        <li class="pager__item pager__item--ellipsis" role="presentation">&hellip;</li>
+        <li role="presentation">&hellip;</li>
       {% endif %}
       {# Print next item if we are not on the last page. #}
       {% if items.next %}
-        <li class="pager__item pager__item--next">
+        <li>
           <a href="{{ items.next.href }}" title="{{ 'Go to next page'|t }}" rel="next"{{ items.next.attributes }}>
             <span class="visually-hidden">{{ 'Next page'|t }}</span>
             <span aria-hidden="true">{{ items.next.text|default('next ›'|t) }}</span>
@@ -88,7 +88,7 @@
       {% endif %}
       {# Print last item if we are not on the last page. #}
       {% if items.last %}
-        <li class="pager__item pager__item--last">
+        <li>
           <a href="{{ items.last.href }}" title="{{ 'Go to last page'|t }}"{{ items.last.attributes }}>
             <span class="visually-hidden">{{ 'Last page'|t }}</span>
             <span aria-hidden="true">{{ items.last.text|default('last »'|t) }}</span>
diff --git a/core/modules/system/templates/progress-bar.html.twig b/core/modules/system/templates/progress-bar.html.twig
index 885a80f..df482c3 100644
--- a/core/modules/system/templates/progress-bar.html.twig
+++ b/core/modules/system/templates/progress-bar.html.twig
@@ -13,11 +13,11 @@
  * @ingroup themeable
  */
 #}
-<div class="progress" data-drupal-progress>
+<div data-drupal-progress>
   {% if label %}
-    <div class="progress__label">{{ label }}</div>
+    <div>{{ label }}</div>
   {% endif %}
-  <div class="progress__track"><div class="progress__bar" style="width: {{ percent }}%"></div></div>
-  <div class="progress__percentage">{{ percent }}%</div>
-  <div class="progress__description">{{ message }}</div>
+  <div><div style="width: {{ percent }}%"></div></div>
+  <div>{{ percent }}%</div>
+  <div>{{ message }}</div>
 </div>