<html>
<head>
<style>
/* 默认的 CSS 值 */
h2 {
display: block;
font-size: 1.5em;
margin-top: 0.83em;
margin-bottom: 0.83em;
margin-left: 0;
margin-right: 0;
font-weight: bold;
}
</style>
</head>
<body>
<p>默认情况下,h2 元素会这样显示:</p>
<h2>This is heading 2</h2>
<p>自定义的 h2 元素(更改 font-weight):</p>
<h2 style="font-weight:normal;">This is heading 2</h2>
</body>
</html>