<!DOCTYPE html>
<html>
<head>
<script src="/lib/jquery-1.12.2.min.js"></script>
<script>
$(document).ready(function(){
$("p").on("mouseover mouseout", function(){
$(this).toggleClass("intro");
});
});
</script>
<style>
.intro {
font-size: 150%;
color: red;
}
</style>
</head>
<body>
<p>Move the mouse pointer over this paragraph.</p>
</body>
</html>