<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>清除浮动</title>
<style type="text/css">
ul{list-style:none;outline:1px solid;}
ul li{padding:5px 8px;background:#ccc;float:left;margin-right:8px;}
.clearfix:after{clear:both;content:'';display:block; 0;height: 0;font-size:0;visibility:hidden;}
.box2{overflow:hidden;}
.box3{overflow:auto;}
.box4{height:31px;}
</style>
</head>
<body>
<ul class="clearfix box1">
<li>11</li>
<li>22</li>
<li>33</li>
</ul>
<ul class="box2">
<li>11</li>
<li>22</li>
<li>33</li>
</ul>
<ul class="box3">
<li>11</li>
<li>22</li>
<li>33</li>
</ul>
<ul class="box4">
<li>11</li>
<li>22</li>
<li>33</li>
</ul>
</body>
</html>