jQuery, CSS and HTML
<!DOCTYPE html>
<head>
<script src="//code.jquery.com/jquery-1.10.2.js"></script>
<script>
$(document).ready(function(){
    $("#div_alert").click(function(){
    alert("A simple jQuery/JS alert!");
    });
});
</script>

<style>
#div_alert {
  background: #4C9B79;
  height: 220px;
  width:40%;
  border-radius: 15px;
  padding:20px;
  font-size:18px;
  color:#fff;   
}
</style>
</head>
<body>

<div id="div_alert">Click anywhere in this div!</div>

</body>
</html>
Click anywhere in this div!