.css-selector {
    background: linear-gradient(266deg, #047457, #2aa0cc, #3cb1bd, #2db9a8);
    background-size: 800% 800%;

    -webkit-animation: AnimationName 22s ease infinite;
    -moz-animation: AnimationName 22s ease infinite;
    -o-animation: AnimationName 22s ease infinite;
    animation: AnimationName 22s ease infinite;
}

@-webkit-keyframes AnimationName {
    0%{background-position:42% 0%}
    50%{background-position:59% 100%}
    100%{background-position:42% 0%}
}
@-moz-keyframes AnimationName {
    0%{background-position:42% 0%}
    50%{background-position:59% 100%}
    100%{background-position:42% 0%}
}
@-o-keyframes AnimationName {
    0%{background-position:42% 0%}
    50%{background-position:59% 100%}
    100%{background-position:42% 0%}
}
@keyframes AnimationName {
    0%{background-position:42% 0%}
    50%{background-position:59% 100%}
    100%{background-position:42% 0%}
}