1、父元素设置为 overflow:hidden
2、添加同级元素
<div class="clear"></div>
.clear{ clear:both; }
3、父元素:after
1 .parent:after{ 2 width: 0; 3 height: 0; 4 clear:both; 5 content:' '; 6 display:block; 7 visibility:hidden; 8 }