diff -u b/core/themes/classy/classy.libraries.yml b/core/themes/classy/classy.libraries.yml
--- b/core/themes/classy/classy.libraries.yml
+++ b/core/themes/classy/classy.libraries.yml
@@ -5,7 +5,7 @@
       css/layout.css: {}
       # We can not attach this in the item-list.html.twig template since it is
       # often used during RendererInterface::renderPlain().
-      css/dataset/item.list.css: {}
+      css/dataset/item-list.css: {}
 
 book-navigation:
   version: VERSION
reverted:
--- b/core/themes/classy/css/dataset/item.list.css
+++ /dev/null
@@ -1,38 +0,0 @@
-/**
- * @file
- * Styling for item lists.
- */
-.item-list .title {
-  font-weight: bold;
-}
-.item-list ul {
-  margin: 0 0 0.75em 0;
-  padding: 0;
-}
-.item-list ul li {
-  margin: 0 0 0.25em 1.5em; /* LTR */
-  padding: 0;
-}
-[dir="rtl"] .item-list ul li {
-  margin: 0 1.5em 0.25em 0;
-}
-div.item-list__comma-list {
-  display: inline;
-}
-/**
- * Comma separated lists inside lists.
- */
-.item-list ul.item-list__comma-list {
-  display: inline;
-}
-.item-list ul.item-list__comma-list li {
-  display: inline;
-  list-style-type: none;
-}
-.item-list .item-list__comma-list,
-.item-list .item-list__comma-list li,
-[dir="rtl"] .item-list .item-list__comma-list,
-[dir="rtl"] .item-list .item-list__comma-list li {
-  margin: 0;
-  padding: 0;
-}
only in patch2:
unchanged:
--- /dev/null
+++ b/core/themes/classy/css/dataset/item-list.css
@@ -0,0 +1,38 @@
+/**
+ * @file
+ * Styling for item lists.
+ */
+.item-list .title {
+  font-weight: bold;
+}
+.item-list ul {
+  margin: 0 0 0.75em 0;
+  padding: 0;
+}
+.item-list ul li {
+  margin: 0 0 0.25em 1.5em; /* LTR */
+  padding: 0;
+}
+[dir="rtl"] .item-list ul li {
+  margin: 0 1.5em 0.25em 0;
+}
+div.item-list__comma-list {
+  display: inline;
+}
+/**
+ * Comma separated lists inside lists.
+ */
+.item-list ul.item-list__comma-list {
+  display: inline;
+}
+.item-list ul.item-list__comma-list li {
+  display: inline;
+  list-style-type: none;
+}
+.item-list .item-list__comma-list,
+.item-list .item-list__comma-list li,
+[dir="rtl"] .item-list .item-list__comma-list,
+[dir="rtl"] .item-list .item-list__comma-list li {
+  margin: 0;
+  padding: 0;
+}