清除浮动

◇clear：both

<div style="float:left">……</div><div style="clear:both"></div>

◇给父元素设置overflow属性

<div style="overflow:hidden">    <div>……</div></div>

◇使用伪元素：after

<style type="text/css">    .clearfix:after{        content:"";        height:0;        line-height:0;        display:block;        clear:both;        visibility:hidden;    }    .clearfix{        /*兼容IE*/        zoom:1;    }</style><div class="clearfix">    <div>……</div></div>