.animation-box {
    height: 0.7em;
}

.animation {
    height: 0.7em;
    width: 8em;
    border-radius: 3em;
    background-color: #00D2AA;
    position: absolute;
    animation: pebble 2s infinite linear alternate;
}

@keyframes pebble {
    0% {
        transform: translateX(0);
    }
    100% {
        transform: translateX(calc(100vw - 100%));
    }
}