<div style="position: relative;width:800px;height: 300px;background-color: gainsboro;border:1px solid red;margin: 0 auto"> ???<div style="position: absolute;width:100px;height: 100px;bottom: 0;left: 0;background-color: brown"> ???</div></div><div style="position: relative;width:800px;height: 300px;background-color: gainsboro;border:1px solid red;margin: 0 auto"> ???<div style="position: absolute;width:100px;height: 100px;top: 0;right: 0;background-color: brown"> ???</div></div><div style="position: relative;width:800px;height: 300px;background-color: gainsboro;border:1px solid red;margin: 0 auto"> ???<div style="position: absolute;width:100px;height: 100px;bottom:0;background-color: brown"> ???</div></div>
当需要下层DIV在上层DIV中定位时，上层DIV使用relative,下层DIV使用absolute.配合TOP,LEFT,RIGHT,BOTTOM定位。
DIV(CSS 定位)
原文地址：http://www.cnblogs.com/GabyGU/p/7786861.html