diff --git a/core/modules/system/templates/container.html.twig b/core/modules/system/templates/container.html.twig
index 2f71632..167965c 100644
--- a/core/modules/system/templates/container.html.twig
+++ b/core/modules/system/templates/container.html.twig
@@ -20,6 +20,7 @@
 {%
   set classes = [
     has_parent ? 'js-form-wrapper',
+    has_parent ? 'form-wrapper',
   ]
 %}
 <div{{ attributes.addClass(classes) }}>{{ children }}</div>
diff --git a/core/modules/system/templates/fieldset.html.twig b/core/modules/system/templates/fieldset.html.twig
index 4e84b83..b44a2c8 100644
--- a/core/modules/system/templates/fieldset.html.twig
+++ b/core/modules/system/templates/fieldset.html.twig
@@ -25,6 +25,7 @@
   set classes = [
     'form-item',
     'js-form-wrapper',
+    'form-wrapper',
   ]
 %}
 <fieldset{{ attributes.addClass(classes) }}>