diff --git a/ch02/listing-2.13.html b/ch02/listing-2.13.html
index bee3a55..5c8a2f7 100644
--- a/ch02/listing-2.13.html
+++ b/ch02/listing-2.13.html
@@ -34,7 +34,7 @@
     }
 
     .panel.large {
-      font-size: 1.2em;
+      font-size: 1.2rem;
     }
   </style>
 </head>