一. 伪元素清除浮动(推荐)

清除浮动div 包裹浮动div

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <style>
        /*伪元素作父级包裹浮动*/
        .clear::before,.clear::after{
            content:"";
            display: block;  /*将伪元素增加的内容设置成块元素*/
            clear:both;
        }
        /*浮动*/
        box{
            float:left;
        }
    </style>
</head>
<body>
    <div class="clear">
        <div class="box"></div>
    </div>
</body>
</html>

二. 空div清除浮动

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <style>
        /*清除浮动*/
        .clear{
            clear:both;
        }
        /*浮动*/
        .box{
            width:200px;
            height:200px;
            background-color: #f00;
            float:left;
        }

    </style>
</head>
<body>
    <div>
        <div class="box"></div>
        <div class="clear"></div>
    </div>
    <h3>浮动元素下面的元素</h3>
</body>
</html>

CSS: 清除浮动

一. 伪元素清除浮动(推荐)

二. 空div清除浮动