How to place a DIV over another DIV using CSS

  <div id="div1" style="background-color: #F79647; border: 2px solid #B16C31; height: 80px;
        width: 200px; position: relative; top: 10px">
        DIV1
    </div>
    <div id="div2" style="background-color: #FFFF2A; border: 2px solid #CDCD16; height: 80px;
        width: 180px;margin-left:10px">
        DIV2
    </div>