js弹层问题，急。。。

Question

在火狐浏览器不兼容，遮罩层没有透明度。<style type="text/css">
        #massage_box
        {
            position: absolute;
            z-index:9999;
            top: 50%;
            left: 50%;
            width: 400px;
            height: 200px;
            background: #fff;
            margin: -102px 0 0 -202px;
            display: none;
        }
        #mask
        {
            background-color: #666666;
            z-index:1;
            position: absolute;
            width:1024px;
            height:1000px;
            opacity=0.5; 
            display: none;
            filter: alpha(opacity=50);
            -moz-opacity: 0.5;
        }
        .massage
        {
            border: #036 solid;
            border-width: 1 1 3 1;
            width: 95%;
            height: 95%;
            background: #fff;
            color: #036;
            font-size: 12px;
            line-height: 150%;
        }
        .header
        {
            background: #036;
            height: 10%;
            font-family: Verdana, Arial, Helvetica, sans-serif;
            font-size: 12px;
            padding: 0 0 0 0;
            color: #fff;
        }
        .font
        {
            font-size: 14px;
        }
    </style>    <script type="text/javascript">
    
    var Obj=''   
document.onmouseup=MUp   
document.onmousemove=MMove  function MDown(Object){   
    Obj=Object.id   
    document.all(Obj).setCapture()   
    pX=event.x-document.all(Obj).style.pixelLeft;   
    pY=event.y-document.all(Obj).style.pixelTop;   
}  //鼠标移动
function MMove(){   
    if(Obj!=''){   
        document.all(Obj).style.left=event.x-pX;   
        document.all(Obj).style.top=event.y-pY;   
    }   
}  function MUp(){   
    if(Obj!=''){   
        document.all(Obj).releaseCapture();   
        Obj='';   
    }   
}   //弹出层
function d_x(){  
    //mask.style.width = document.body.scrollWidth + "px";  
    //mask.style.height = document.body.scrollHeight + "px";
    //mask.style.left = (parseInt(document.body.scrollWidth) - 1024) / 2 + "px"; // 屏幕居中    
    mask.style.display = "block";
massage_box.style.display = "block" ;}  //取消层
function d_y(){      mask.style.display = "none";
    massage_box.style.display = "none" ;}  

Answer 1

注意红色部分#mask
        {
            background-color: #666666;
            z-index:1;
            position: absolute;
            width:1024px;
            height:1000px;
            opacity:0.5; 
            display: none;
            filter: alpha(opacity=50);
            -moz-opacity: 0.5;
        }

Answer 2

属性啊  opacity在标准浏览器中可以实现透明，如果是IE就可以使用filter

Answer 3

我把 opacity 这个属性去掉还是不行。在火狐浏览器上遮罩层没有透明度。

Answer 4

把-moz-opacity去掉，ff下只要使用opacity:0.5就行了，前面那个已经无效了