servlet_web组件三种关联方式

html, body
{
height: 100%;
margin: 0px;
font-size: 12px;
}

.mydiv
{
background: #f1f1f1;
padding: 15px 30px;
border: 5px solid #ccc;
z-index: 99;
left: 50%; /*FF IE7*/
top: 50%; /*FF IE7*/
margin-left: -150px !important; /*FF IE7 该值为本身宽的一半 */
margin-top: -60px !important; /*FF IE7 该值为本身高的一半*/
margin-top: 0px;
position: fixed !important; /*FF IE7*/
position: absolute; /*IE6*/
_top: expression(eval(document.compatMode &&
document.compatMode=='CSS1Compat') ?
documentElement.scrollTop + (document.documentElement.clientHeight-this.offsetHeight)/2 :/*IE6*/
document.body.scrollTop + (document.body.clientHeight - this.clientHeight)/2); /*IE5 IE5.5*/
}

.bg
{
background-color: #ccc;
width: 100%;
height: 100%;
left: 0;
top: 0; /*FF IE7*/
filter: alpha(opacity=50); /*IE*/
opacity: 0.5; /*FF*/
z-index: 1;
position: fixed !important; /*FF IE7*/
position: absolute; /*IE6*/
_top: expression(eval(document.compatMode &&
document.compatMode=='CSS1Compat') ?
documentElement.scrollTop + (document.documentElement.clientHeight-this.offsetHeight)/2 :/*IE6*/
document.body.scrollTop + (document.body.clientHeight - this.clientHeight)/2); /*IE5 IE5.5*/
}