<div class="container">
    <div class="ball ball1"></div>
    <div class="ball ball2"></div>
    <div class="ball ball3"></div>
</div>
body {
    padding: 1vw;
}

.container {
    text-align: center;
}

.ball {
    display: inline-block;
    width: 1vw;
    height: 1vw;
    background-color: #333;
    margin: 1vh;
    border-radius: 50%;
}

.ball1 {
    animation: move 1s ease-in infinite alternate;
}

.ball2 {
    animation: move 1s linear infinite alternate;
}

.ball3 {
    animation: move 1s ease-out infinite alternate;
}

@keyframes move {
    100% {
        transform: translateY(5vw);
    }
}

External CSS

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External JavaScript

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