body {
    margin: 0;
    overflow: hidden;
    height: 100vh;
    background-color: azure;
}

.box {
    position: absolute;
    width: 16vw;
    height: 7vw;
    border-radius: 20px;
    animation: go-around 6s alternate infinite ease-in-out;
}

@keyframes go-around {
    0% {
        top: 1%;
        left: 0;
        transform: rotate(0deg);
        background-color: blue;
    }
    25% {
        top: 1%;
        left: calc(100% - 19vw);
        transform: rotate(180deg);
        background-color: yellow;
    }
    50% {
        top: calc(100% - 9vw);
        left: calc(100% - 19vw);
        transform: rotate(360deg);
        background-color: red;
    }
    75% {
        top: calc(100% - 9vw);
        left: 0;
        transform: rotate(180deg);
        background-color: hotpink;
    }
    100% {
        top: 1%;
        left: 0;
        transform: rotate(360deg);
        background-color: orange;
    }
}