diff --git a/core/themes/classy/css/components/form.css b/core/themes/classy/css/components/form.css
index a752a32283..93b719146c 100644
--- a/core/themes/classy/css/components/form.css
+++ b/core/themes/classy/css/components/form.css
@@ -32,7 +32,11 @@ form .field-add-more-submit {
   margin-top: 1em;
   margin-bottom: 1em;
 }
-/* Limit scope of margin reset rule to only-child. */
+
+/**
+ * Limit scope of margin reset rule to only-child to allow form items inside
+ * table elements to have a margin top and bottom.
+ */
 tr.odd td > .form-item:only-child,
 tr.even td > .form-item:only-child {
   margin-top: 0;