diff --git a/demo/_includes/layout.vto b/demo/_includes/layout.vto
index 73d66d0..b32e6c5 100644
--- a/demo/_includes/layout.vto
+++ b/demo/_includes/layout.vto
@@ -80,6 +80,9 @@
         opacity: 0.8;
       }
       pre {
+        display: block;
+        margin-left: auto;
+        margin-right: auto;
         padding-top: 7px !important;
         padding-bottom: 7px !important;
         font-size: 1.6vh !important;