Update cart-builder.html

Author: Shen-wb

barcode-scanner-api-samples/scan-multiple-barcodes/cart-builder.html

@@ -83,7 +83,7 @@
       border-radius: 8px;
       box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
       cursor: move;
-      z-index: 9999;
+      z-index: 999;
       padding: 3px;
       box-sizing: border-box;
     }