.css-selector {
    background: linear-gradient(55deg, #fafefd, #faf477, #fae47f);
    background-size: 600% 600%;

    -webkit-animation: AnimationName 4s ease infinite;
    -moz-animation: AnimationName 4s ease infinite;
    -o-animation: AnimationName 4s ease infinite;
    animation: AnimationName 4s ease infinite;
}

@-webkit-keyframes AnimationName {
    0% {
        background-position: 0% 82%
    }

    50% {
        background-position: 100% 19%
    }

    100% {
        background-position: 0% 82%
    }
}

@-moz-keyframes AnimationName {
    0% {
        background-position: 0% 82%
    }

    50% {
        background-position: 100% 19%
    }

    100% {
        background-position: 0% 82%
    }
}

@-o-keyframes AnimationName {
    0% {
        background-position: 0% 82%
    }

    50% {
        background-position: 100% 19%
    }

    100% {
        background-position: 0% 82%
    }
}

@keyframes AnimationName {
    0% {
        background-position: 0% 82%
    }

    50% {
        background-position: 100% 19%
    }

    100% {
        background-position: 0% 82%
    }
}