:root {
    --container-dimensions: 300px;

    --ball-height: calc(var(--container-dimensions) / 4);
    --animation-duration: 3s;
}

body,
html {
    height: 100%;
}

body {
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: #36399a;
}

.container {
    height: var(--container-dimensions);
    width: var(--container-dimensions);
    position: relative;
    padding: 40px;
}

.ball {
    height: var(--ball-height);
    width: var(--ball-height);
    border-radius: 100%;
    position: absolute;
    top: calc(50% - calc(var(--ball-height) / 2));
}

.ball:nth-child(1) {
    transform: translateX(0%);
    border-radius: 50px;
    background-color: #7174db;
    animation: move-1 var(--animation-duration) linear infinite;
}

.ball:nth-child(2) {
    transform: translateX(150%) scale(1.5);
    border-radius: 50px;
    background-color: #e52a6e;

    animation: move-2 var(--animation-duration) linear infinite;
}

.ball:nth-child(3) {
    transform: translateX(300%);
    background-color: #fed430;

    animation: move-3 var(--animation-duration) linear infinite;
}

@keyframes move-1 {
    0% {
        transform: translateX(0%) scale(1);
        z-index: 0;
    }

    23%,
    33% {
        transform: translateX(150%) scale(1.5);
        z-index: 10;
    }

    56%,
    66% {
        transform: translateX(300%) scale(1);
        z-index: 0;
    }

    90%,
    100% {
        transform: translateX(0%) scale(1);
        z-index: 0;
    }
}

@keyframes move-2 {
    0% {
        transform: translateX(150%) scale(1.5);
        z-index: 10;
    }

    23%,
    33% {
        transform: translateX(300%) scale(1);
        z-index: 0;
    }

    56%,
    66% {
        transform: translateX(0%) scale(1);
        z-index: 0;
    }

    90%,
    100% {
        transform: translateX(150%) scale(1.5);
        z-index: 10;
    }
}

@keyframes move-3 {
    0% {
        transform: translateX(300%) scale(1);
        z-index: 0;
    }

    23%,
    33% {
        transform: translateX(0%) scale(1);
        z-index: 0;
    }

    56%,
    66% {
        transform: translateX(150%) scale(1.5);
        z-index: 10;
    }

    90%,
    100% {
        transform: translateX(300%) scale(1);
        z-index: 0;
    }
}