SnowFlake.css

body {
    margin: 0;
    background-color: darkblue;
    overflow: hidden;
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
}

.snowflake-area {
    position: relative;
    width: 100%;
    height: 100%;
}

.snowflake {
    position: absolute;
    top: -5%;
    font-size: 2rem;
    animation: fall linear infinite;
    opacity: 0.8;
}

@keyframes fall {
    0% {
        transform: translateY(0) rotate(0deg);
    }
    100% {
        transform: translateY(100vh) rotate(360deg);
    }
}

.snowflake:nth-child(1) {
    left: 10%;
    animation-duration: 5s;
}
.snowflake:nth-child(2) {
    left: 20%;
    animation-duration: 3s;
    font-size: 1.5rem;
}
.snowflake:nth-child(3) {
    left: 30%;
    animation-duration: 6s;
    font-size: 2.5rem;
}
.snowflake:nth-child(4) {
    left: 40%;
    animation-duration: 4s;
}
.snowflake:nth-child(5) {
    left: 50%;
    animation-duration: 7s;
    font-size: 2rem;
}
.snowflake:nth-child(6) {
    left: 60%;
    animation-duration: 4.5s;
    font-size: 2.2rem;
}
.snowflake:nth-child(7) {
    left: 70%;
    animation-duration: 6.5s;
}
.snowflake:nth-child(8) {
    left: 80%;
    animation-duration: 3.5s;
    font-size: 1.8rem;
}
.snowflake:nth-child(9) {
    left: 90%;
    animation-duration: 5.5s;
}
.snowflake:nth-child(10) {
    left: 95%;
    animation-duration: 4s;
    font-size: 2.3rem;
}