.popup {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.8);
    z-index: 999;
    justify-content: center;
    align-items: center;
}

.popup img {
    max-width: 90%;
    max-height: 90%;
}

.popup .close-btn {
    position: absolute;
    top: 20px;
    right: 20px;
    font-size: 30px;
    color: white;
    cursor: pointer;
}

.popup:target {
    display: flex;
}