style.css

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    user-select: none;
}

body{
    overflow: hidden;
}

section{
    height: 100vh;
    overflow: hidden;
    background: #091921;
}

section span{
    position: absolute;
    top: -1000px;
    background: white;
    /* border-radius: 50%; */
    background-size: cover;
    animation: anime 5.5s linear forwards;
    /* animation-iteration-count: infinite; */
    /* animation-fill-mode: forwards; */
}

@keyframes anime {
    0% {
        transform: translateY(555px);
    }
    50% {
        opacity: 1;
    }
    100% {
        transform: translateY(1000%);
        /* transform: translateY(-1000%); */
        opacity: 0;
    }
}

@media screen and (min-width: 300px) and (max-width: 800px) {
    body {
        background: #091921;
    }
    
    section {
        width: 100%;
        height: 100%;
    }
}