效果:

HTML:
页面正在加载中...
CSS:
*html{
background-image:url(about:blank);
background-attachment:fixed;
}
.panel-mask{
display: none;
width: 100%;
height: 100%;
background-color: rgba(0,0,0,0.3);/* IE9、标准浏览器、IE6和部分IE7内核的浏览器(如QQ浏览器)会读懂 */
position: fixed;
top: 0px;
_position:absolute;
_bottom:auto;
_top:expression(eval(document.documentElement.scrollTop+document.documentElement.clientHeight-this.offsetHeight-(parseInt(this.currentStyle.marginTop,10)||0)-(parseInt(this.currentStyle.marginBottom,10)||0)));
}
.panel-mask .panel-mask-loading{
width: 400px;
text-align: center;
font-size: 16px;
position: absolute;
top: 50%;
left: 50%;
margin-top: -25px;
margin-left: -200px;
margin-bottom: 0px;
}
@media \0screen\,screen\9 {/* 只支持IE6、7、8 */
.panel-mask{
background-color:#000000;
filter:Alpha(opacity=30);
position:static; /* IE6、7、8只能设置position:static(默认属性) ,否则会导致子元素继承Alpha值 */
*zoom:1; /* 激活IE6、7的haslayout属性,让它读懂Alpha */
}
.panel-mask .panel-mask-loading{
position: relative;/* 设置子元素为相对定位,可让子元素不继承Alpha值 */
}
}