img{
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
}

body {
    background: linear-gradient(270deg, #22faef, #ff6bf8);
    background-size: 400% 400%;

    animation: AnimationName 34s ease infinite;
}

@keyframes AnimationName {
    0%{background-position:0% 50%}
    50%{background-position:100% 50%}
    100%{background-position:0% 50%}
}