diff --git a/lesson.css b/lesson.css
index b97b17a..0b914df 100644
--- a/lesson.css
+++ b/lesson.css
@@ -51,6 +51,7 @@ div.out:before {
 /* Error output. */
 .err {
     color: darkred;
+    margin-left: 20px;
     font-style: italic;
     font-weight: bold;
 }