diff --git a/preview/index.html b/preview/index.html
index f0b2888..b911ef8 100644
--- a/preview/index.html
+++ b/preview/index.html
@@ -19,6 +19,9 @@
height: 30vh;
width: 100%;
font-size: 14px;
+ max-width: 800px;
+ margin: 0 auto;
+ display: block;
}