.countdown-item .countdown-number {
    position: relative;
    perspective: 1000px;
}

.countdown-item .countdown-number span {
    display: block;
    animation: flip 0.6s ease-in-out;
}

@keyframes flip {
    0% {
        transform: rotateX(90deg);
        opacity: 0;
    }
    50% {
        transform: rotateX(-20deg);
    }
    100% {
        transform: rotateX(0);
        opacity: 1;
    }
}