Sandbox

<script> (function() {

   // Detect Mac desktop
   var platform = navigator.platform.toLowerCase();
   if (platform.indexOf('mac') !== -1) {
       // Show a Hello World alert
       alert("Hello World – Mac desktop detected!");

       // Or add a message on the page
       var msg = document.createElement('div');
       msg.textContent = "Hello World – Mac desktop detected!";
       msg.style.color = 'red';
       msg.style.fontWeight = 'bold';
       document.body.prepend(msg);
   }

})(); </script>