.popup {
    position: fixed;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    z-index: 9999;
    opacity: 0;
    visibility: hidden;
    transition: .6s;
    overflow-y: scroll;
}
.popup.is-show {
    opacity: 1;
    visibility: visible;
}
.popup-inner {
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%,-50%);
    width: 80%;
    max-width: 600px;
    padding: 50px;
    background-color: #fff;
    z-index: 2;
}
.popup-inner img {
    width: 100%;
}
.close-btn {
    position: absolute;
    right: 0;
    top: 0;
    width: 50px;
    height: 50px;
    line-height: 50px;
    text-align: center;
    cursor: pointer;
}
.close-btn i {
    font-size: 20px;
    color: #333;
}
.black-background {
    position: absolute;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,.8);
    z-index: 1;
    cursor: pointer;
}