clearfix的方式

1.
.clearfix:after{ 
content: "";
display: block;
clear: both;
} 

2.
.clearfix{
overflow: auto;
_height: 1%;
}
3.
.clearfix{
overflow: hidden;
_zoom: 1;
}
4.
.clearfix:after{
content: "";
display: block;
clear: both;

5.最佳
.clearfix{
*zoom: 1;
}
.clearfix:before,.clearfix:after{
display: table;
content: "";
}
.clearfix:after{
clear: both;
}