清除浮动的方式

一、

clear:both;

clear:left;

clear:right

二、让父元素清除浮动，使其不至于因子元素的浮动而塌陷

overthrow:hidden;(100%或者固定宽度)

三、利用伪类

.clearfix::before,
.clearfix::after {
content: ".";
display: block;
height: 0;
visibility: hidden;
clear:both;
}
.clearfix {zoom: 1;}//兼容IE6,7