如何用CSS设置下拉列表sel

div {
        border:1px solid #C0C0C0;
        width:183px;
        height:18px;
        clip:rect(0px,18px,22px,0px);
        overflow:hidden;
}
select {
        position:relative;
        left:-2px;
        top:-2px;
        font-size:12px;
        width:185px;
        line-height:18px;border:0px;
        color:#909993;
}