diff --git a/chem.html b/chem.html
index 4d4490f..949f95d 100644
--- a/chem.html
+++ b/chem.html
@@ -24,7 +24,7 @@
     </script>
       <script>
         (function() {
-            if (window.innerWidth < 800) {
+            if (screen.width < 800) {
                 // Create popup div
                 var popup = document.createElement('div');
                 popup.id = 'mobileWarning';