.pop-img-wrap {
    position: fixed;
    width: 100%;
    height: 100%;
    top: 0;
    left: 0;
    z-index: 999;
    background: rgba(0, 0, 0, .4);
    display: none;
}
.pop-img {
    max-width: 800px;
    height: auto;
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translateX(-50%) translateY(-50%);
}