遮罩样式（支持IE和FireFox）

.gSys-msg .mask
        {
            background-color: #000000;
            height: 100%;
            left: 0;
            filter:alpha(opacity=30);
            opacity:0.3;
            overflow: hidden;
            position: absolute;
            top: 0;
            width: 100%;
            z-index: 900;
        }

 

其中  filter:alpha(opacity=30); 支持IE的遮罩效果

       opacity:0.3; 支持Firefox的遮罩效果

转载于:https://www.cnblogs.com/macroxu-1982/archive/2011/01/25/1944939.html