.popup-hidden {
    display: none;
}

.popup {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    justify-content: center;
    align-items: center;
}

.popup-content {
    background: white;
    padding: 20px;
    border-radius: 8px;
    text-align: center;
}

#preview {
    margin-top: 10px;
    max-width: 100%;
    max-height: 300px;
}