HTMLify

body {
    background: #151515;
    display: grid;
    place-items: center;
    height: 100vh;
}

#loader {
    width: 100px;
    height: 40px;
    position: absolute;
}

#loader div {
    width: 20px;
    height: 20px;
    background: #fff;
    border-radius: 50%;
    position: absolute;
}

#d1 {
    animation: animate 2s linear infinite;
}

#d2 {
    animation: animate 2s linear infinite -0.4s;
}

#d3 {
    animation: animate 2s linear infinite -0.8s;
}

#d4 {
    animation: animate 2s linear infinite -1.2s;
}

#d5 {
    animation: animate 2s linear infinite -1.6s;
}

@keyframes animate {
    0% {
        left: 100px;
        top: 0;
    }

    80% {
        left: 0;
        top: 0;
    }

    85% {
        left: 0;
        top: -20px;
        width: 20px;
        height: 20px;
    }

    90% {
        width: 40px;
        height: 15px;
    }

    95% {
        left: 100px;
        top: -20px;
        width: 20px;
        height: 20px;
    }

    100% {
        left: 100px;
        top: 0;
    }
}