diff --git a/src/backend/demo/data/template/css.txt b/src/backend/demo/data/template/css.txt
index c3eee9e12..8856136a2 100644
--- a/src/backend/demo/data/template/css.txt
+++ b/src/backend/demo/data/template/css.txt
@@ -13,3 +13,6 @@ body {
 .body{
   margin-top: 1.5rem
 }
+img {
+  max-width: 100%;
+}