diff --git a/core/modules/comment/comment.theme-rtl.css b/core/modules/comment/comment.theme-rtl.css
new file mode 100644
index 0000000000000000000000000000000000000000..c12102389834ba8495e93e3170c0b4a14bcf6c86
--- /dev/null
+++ b/core/modules/comment/comment.theme-rtl.css
@@ -0,0 +1,13 @@
+
+/**
+ * @file
+ * RTL styles for comment module.
+ */
+
+/**
+ * Indent threaded comments.
+ */
+.indented {
+  margin-left: 0;
+  margin-right: 25px;
+}
diff --git a/core/modules/comment/comment.theme.css b/core/modules/comment/comment.theme.css
new file mode 100644
index 0000000000000000000000000000000000000000..6a32a633847ceb52119b911ace85dfbbb152d5b0
--- /dev/null
+++ b/core/modules/comment/comment.theme.css
@@ -0,0 +1,12 @@
+
+/**
+ * @file
+ * Basic styling for comment module.
+ */
+
+/**
+ * Indent threaded comments.
+ */
+.indented {
+  margin-left: 25px; /* LTR */
+}