diff --git a/index.html b/index.html
index 9ab95dc..aee9d8d 100644
--- a/index.html
+++ b/index.html
@@ -44,6 +44,7 @@
     border: 1px solid #000;
     padding: 5px 2px;
     font-size: 14px;
+    user-select: none;
   }
 
   .zerox-col {