简单遮罩层

 <style type="text/css">
        #zzc_bg
        {
            display: none;
            position: absolute;
            top: 0%;
            left: 0%;
            width: 100%;
            height: 100%;
            background-color: black;
            z-index: 1001;
            -moz-opacity: 0.7;
            opacity: .70;
            filter: alpha(opacity=70);
        }
        #zzc_show
        {
            display: none;
            position: absolute;
            top: 38%;
            left: 45%;
            width: 53%;
            z-index: 1002;
        }
        #zzc_show span
        {
            font-size: 35px;
            font-weight: bold;
            color: White;
        }
        #zzc_show img
        {
            width: 50px;
            height: 50px;
        }
    </style>

 <div id="zzc_bg">
    </div>
    <div id="zzc_show">
        <span>98%</span>
        <img src="../images/yuya_load.gif" />
    </div>

<script type="text/javascript" language="javascript">
var zzc_div = {
        showdiv: function () {
            document.getElementById("zzc_bg").style.height = window.screen.availHeight > document.body.clientHeight ? window.screen.availHeight : document.body.clientHeight;
            document.getElementById("zzc_bg").style.display = "block";
            document.getElementById("zzc_show").style.display = "block";
        },
        hidediv: function hidediv() {
            document.getElementById("zzc_bg").style.display = ‘none‘;
            document.getElementById("zzc_show").style.display = ‘none‘;
        }
    }
</script>