.black_overlay {
    display: none;
    position: absolute;
    top: 0%;
    left: 0%;
    width: 100%;
    height: 100%;
    background-color: #ffffff;
    z-index: 1001;
    -moz-opacity: 0.8;
    opacity: .80;
    filter: alpha(opacity=80);
}

.white_content {
    display: none;
    position: absolute;
    top: 10%;
    left: 30%;
    background-color: white;
    z-index: 1002; /* 数字的大小指明了div的相对层，数字大的在上层 */
    overflow: auto;
}

.ewmwb {
    margin-top: 10px;
    font-size: 20px;
    text-align: center;
    color: #eb4124;
}