#overlay {
    position: fixed;
    display: none;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.8);
    z-index: 2;
}

#popup-content {
    background-color: white;
    padding: 10px;
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    margin: auto;
    width: 600px;
    height: 600px;
    z-index: 3;
}

#popup-content img {
    max-width: 100%;
    height: auto;
}

#close {
    display: inline-block;
    position: absolute;
    right: -40px;
    top: -40px;
    z-index: 99999;
}

@media screen and (max-width:900px) {
    #popup-content {
        width: 400px;
        height: 400px;
    }
}

@media screen and (max-width:500px) {
    #popup-content {
        width: 250px;
        height: 250px;
    }
    #close {
        right: 0;
    }
}