diff --git a/theme/ydoc-theme-demo/style.css b/theme/ydoc-theme-demo/style.css
index b166dbdd..60d5467d 100644
--- a/theme/ydoc-theme-demo/style.css
+++ b/theme/ydoc-theme-demo/style.css
@@ -15,10 +15,13 @@
 }
 
 html {
+  height: 100%;
   font-size: 100px;
 }
 
 body {
+  width: 100%;
+  height: 100%;
   font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Helvetica, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", SimSun, sans-serif;
   font-size: 14px;
   color: rgba(3, 17, 31, 0.87);
@@ -605,15 +608,6 @@ a:link, a:visited {
   }
 }
 
-html {
-  height: 100%;
-}
-
-body {
-  width: 100%;
-  height: 100%;
-}
-
 .slideout-menu {
   position: fixed;
   left: 0;