body {
    background-image: url(./download.jpg );
    background-repeat: no-repeat;
    background-size: cover;
}

img {
    height: 200px;
    position: absolute;
    top: 300px;
    left: 600px;
    animation: float 1s linear infinite alternate ;
}

@keyframes float {

    0% {
        top: 300px;
        left: 600px;
    }

    100% {
        top: 100px;
        left: 400px;
    }

}