owerflow的滚动条（代码）
<!DOCTYPE html>
<html
lang="en">
<head>
<meta
charset="utf-8">
<style
type="text/css">
p{
width:
300px;
height:
300px;
border:
1px solid green;
overflow:
scroll; /* 添加滚动条 */
/* hidden 将超出部分进行隐藏 */
/* auto
如果内容超出盒子，那么给盒子设置滚动条，如果内容没有超出盒子，那么不显示滚动条。 */
}
</style>
</head>
<body>
<p>
<p>asdfasdfasdf</p>
<p>asdfasdfasdf</p>
<p>asdfasdfasdf</p>
<p>asdfasdfasdf</p>
<p>asdfasdfasdf</p>
<p>asdfasdfasdf</p>
<p>asdfasdfasdf</p>
<p>asdfasdfasdf</p>
<p>asdfasdfasdf</p>
<p>asdfasdfasdf</p>
<p>asdfasdfasdf</p>
<p>asdfasdfasdf</p>
</p>
</body>
</html>