diff --git a/core/modules/block/templates/block-list.html.twig b/core/modules/block/templates/block-list.html.twig
index 854d3ce..29c3647 100644
--- a/core/modules/block/templates/block-list.html.twig
+++ b/core/modules/block/templates/block-list.html.twig
@@ -13,11 +13,6 @@
  * @ingroup themeable
  */
 #}
-<div class="layout-block-list clearfix">
-  <div class="layout-region block-list-primary">
-    {{ form|without('place_blocks') }}
-  </div>
-  <div class="layout-region block-list-secondary">
-    {{ form.place_blocks }}
-  </div>
+<div>
+  {{ form }}
 </div>
diff --git a/core/modules/block/templates/block.html.twig b/core/modules/block/templates/block.html.twig
index aa750cb..3a186b3 100644
--- a/core/modules/block/templates/block.html.twig
+++ b/core/modules/block/templates/block.html.twig
@@ -34,12 +34,6 @@
  * @ingroup themeable
  */
 #}
-{%
-  set classes = [
-    'block',
-    'block-' ~ configuration.provider|clean_class,
-  ]
-%}
 <div{{ attributes.addClass(classes) }}>
   {{ title_prefix }}
   {% if label %}
diff --git a/core/modules/block/templates/block-list.html.twig b/core/themes/classy/templates/block-list.html.twig
similarity index 100%
copy from core/modules/block/templates/block-list.html.twig
copy to core/themes/classy/templates/block-list.html.twig
diff --git a/core/modules/block/templates/block.html.twig b/core/themes/classy/templates/block.html.twig
similarity index 100%
copy from core/modules/block/templates/block.html.twig
copy to core/themes/classy/templates/block.html.twig