清除浮动

clear

.box{
      width:100px;
      height:100px;
      background-color1:yellow;
      clear:left;
}
    清除左浮动

.box{
      width:100px;
      height:100px;
      background-clor:yellow;
      clear:right;
}
清除右浮动

1.both可以清除对它影响最大的浮动
2.可以解决高度塌陷

.clearfix:after

.clearfix:after{
                content:" ";
                display:hidden;
                clear:both;
  }
谁塌陷就加上clearfix