.snowflake {
    position: fixed;
    top: -10px;
    color: #fff;
    font-size: 1em;
    font-family: Arial, sans-serif;
    text-shadow: 0 0 5px #000;
    user-select: none;
    z-index: 1;
    pointer-events: none;
    animation-name: fall;
    animation-timing-function: linear;
    animation-iteration-count: 1;
}

@keyframes fall {
    0% {
        transform: translateY(-10vh);
    }

    100% {
        transform: translateY(110vh);
    }
}