<html>
<head>
<script src="https://libs.baidu.com/jquery/1.10.2/jquery.min.js">
</script>
<script>
$(document).ready(function(){
$("button").click(function(){
$("h1,h2,p").removeClass("blue");
});
});
</script>
<style type="text/css">
.important
{
font-weight:bold;
font-size:xx-large;
}
.blue
{
color:blue;
}
</style>
</head>
<body>
<h1 class="blue">Heading 1</h1>
<h2 class="blue">Heading 2</h2>
<p class="blue">This is a paragraph.</p>
<p>This is another paragraph.</p>
<br>
<button>Remove class from elements</button>
</body>
</html>