.mask {
    width: 100%;
    height: 100%;
    position: fixed;
    z-index: 999999;
    top: 0;
    left: 0;
    display: none;
    background: rgba(0, 0, 0, 0.6);
}

.mask .img {
    width: 500px;
    height: 390px;
    /*background-color: #fff;*/
    vertical-align:middle;
    margin:150px auto;
}