在线运行代码 - 菜鸟教程

<!DOCTYPE html>
<html>
<head>
<style>p.hometown
{ 
background:yellow;
}
</style>
</head>

<body>
<p>My name is Donald.</p>
<p class="hometown">I live in Ducksburg.</p>

<p>My name is Dolly.</p>
<p class="hometown">I also live in Ducksburg.</p>

</body>
</html>

源代码

动行结果