SOURCE

<div class="box"></div>

.box{
    width: 100px;
    height: 100px;
    border-radius: 100%;
    background: orange;
    margin: 40px;
    animation: round 1.3s ease-in-out 2.7s infinite alternate;
}
@keyframes round{
    0%{
        transform: translate3d(0, 0, 0);
    }
    100%{
        transform: translate3d(0, 20px, 0);
    }
}