diff --git a/style.css b/style.css
index f266c8f..731fd5e 100644
--- a/style.css
+++ b/style.css
@@ -40,3 +40,6 @@ li {
 	margin-bottom: 2px;
 	margin-top: 2px;
 }
+#tree li:hover {
+	outline: thin dotted grey;
+}