.wrap {
    position: relative;
    margin: 0 auto;
    z-index: 0;
}

.wrap .downBtn {
    position: absolute;
    top: 8.0rem;
    left: 20%;
    width: 60%;
    height: 0.99rem;
    background-image: url("../img/btn_download.gif");
    background-size: 100% 100%;
    background-repeat: no-repeat;
}