SOURCE

<div id="clearFloat">
	<div class="box">sun1</div>
	<div class="box">sun2</div>
</div>

#clearFloat {
    background: green;
    border: 2px solid blue;
    /* 这是属性去掉对比下 看看效果 */
    overflow: hidden;
}

#clearFloat .box {
    margin: 5px;
    float: left;
    width: 100px;
    height: 100px;
    background: red;
}