.mask {
    position: relative;
}

.mask:after {
    position: absolute;
    display: block;
    content: '';
    width: 100%;
    height: 100%;
    top: 0;
    left: 0;
    background: #fff;
    filter:alpha(opacity=10);
    -moz-opacity:0.1;
    -khtml-opacity: 0.1;
    opacity: 0.1;
    z-index: 99999;
}