<!DOCTYPE html>
<html>
<head>
<script src="/lib/jquery-1.12.2.min.js"></script>
<script>
$(document).ready(function(){
$("button").click(function(){
$("p, h1").removeClass("head intro main");
});
});
</script>
<style>
.head {
font-size: 2em;
color: green;
}
.intro {
font-size: 120%;
color: red;
}
.main {
font-size: 20px;
color: blue;
}
</style>
</head>
<body>
<h1 class="head">This is a heading</h1>
<p class="intro">This is a paragraph.</p>
<p class="main">This is another paragraph.</p>
<button>Remove the "head", "intro" and "main" class from the selected elements</button>
</body>
</html>