.app-toast {
    position: fixed;
    left: 50%;
    bottom: 72px; /* trên bottom-bar */
    transform: translateX(-50%);
    background: rgba(0,0,0,0.85);
    color: #fff;
    padding: 10px 14px;
    border-radius: 10px;
    font-size: 14px;
    opacity: 0;
    pointer-events: none;
    transition: opacity .25s ease, transform .25s ease;
    z-index: 9999;
}

.app-toast.show {
    opacity: 1;
    transform: translateX(-50%) translateY(-4px);
}