.popup-flash {
    position: fixed;
    top: 20px;
    left: 50%;
    transform: translateX(-50%);
    z-index: 9999;
    background: #222;
    color: #fff;
    padding: 1rem 2rem;
    border-radius: 8px;
    font-size: 1.1rem;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.5s, top 0.5s;
}
.popup-flash.show {
    opacity: 1;
    top: 40px;
    pointer-events: auto;
}
.popup-success {
    background: #28a745;
}
.popup-error {
    background: #dc3545;
}
.popup-warning {
    background: #ffc107;
    color: #222;
}
.popup-info {
    background: #17a2b8;
}