diff --git a/theme/classic.html b/theme/classic.html
index b7b155e..3188f68 100644
--- a/theme/classic.html
+++ b/theme/classic.html
@@ -63,7 +63,7 @@
         .operatediv_close{position:absolute;right:3px;top:3px;}
         .readme{padding:8px;}
         .markdown-body, .customfile{padding:20px;text-align:left}
-        @media only screen and (max-width:480px){
+        @media only screen and (orientation: portrait){
 <!--BackgroundMStart-->
             body{background-repeat:no-repeat;background-size:cover;background-attachment:fixed;background-image:url("<!--BackgroundMUrl-->");}
 <!--BackgroundMEnd-->