diff --git a/core/modules/comment/comment.libraries.yml b/core/modules/comment/comment.libraries.yml
index d19ff93..78c4ff0 100644
--- a/core/modules/comment/comment.libraries.yml
+++ b/core/modules/comment/comment.libraries.yml
@@ -7,12 +7,6 @@ drupal.comment:
     - core/drupal
     - core/drupal.form
 
-drupal.comment.threaded:
-  version: VERSION
-  css:
-    theme:
-      css/comment.theme.css: {}
-
 drupal.comment-by-viewer:
   version: VERSION
   js:
diff --git a/core/modules/comment/css/comment.theme.css b/core/modules/comment/css/comment.theme.css
deleted file mode 100644
index c702161..0000000
--- a/core/modules/comment/css/comment.theme.css
+++ /dev/null
@@ -1,16 +0,0 @@
-
-/**
- * @file
- * Basic styling for comment module.
- */
-
-/**
- * Indent threaded comments.
- */
-.indented {
-  margin-left: 25px; /* LTR */
-}
-[dir="rtl"] .indented {
-  margin-left: 0;
-  margin-right: 25px;
-}
diff --git a/core/themes/classy/classy.libraries.yml b/core/themes/classy/classy.libraries.yml
index 116c86b..590d33e 100644
--- a/core/themes/classy/classy.libraries.yml
+++ b/core/themes/classy/classy.libraries.yml
@@ -3,3 +3,9 @@ base:
   css:
     theme:
       css/layout.css: {}
+
+comment-threaded:
+  version: VERSION
+  css:
+    theme:
+      css/comment/comment.theme.css: {}
\ No newline at end of file
diff --git a/core/themes/classy/css/comment/comment.theme.css b/core/themes/classy/css/comment/comment.theme.css
new file mode 100644
index 0000000..c702161
--- /dev/null
+++ b/core/themes/classy/css/comment/comment.theme.css
@@ -0,0 +1,16 @@
+
+/**
+ * @file
+ * Basic styling for comment module.
+ */
+
+/**
+ * Indent threaded comments.
+ */
+.indented {
+  margin-left: 25px; /* LTR */
+}
+[dir="rtl"] .indented {
+  margin-left: 0;
+  margin-right: 25px;
+}
diff --git a/core/themes/classy/templates/content/comment.html.twig b/core/themes/classy/templates/content/comment.html.twig
index 1d56d08..1044364 100644
--- a/core/themes/classy/templates/content/comment.html.twig
+++ b/core/themes/classy/templates/content/comment.html.twig
@@ -63,6 +63,7 @@
  * @see template_preprocess_comment()
  */
 #}
+{{ attach_library('classy/comment-threaded') }}
 {%
   set classes = [
     'comment',