清除浮動

清除浮動的方法有好多種，我個人常用的是以下兩個方法

<div class="clearfix">
    <div class="left">123</div>
    <div class="right">aaa</div>
  </div>

方法一：給父元素添加clearfix

		.left {
			float: left;
		}
		.right {
			float: right;
		}
        .clearfix: before,
        .clearfix: after {
            display: table;
            content: ""; 
        }

        .clearfix: after {
            clear: both;
        }

        .clearfix {
            *zoom: 1;
        }

方法二：給父元素設置固定的高