html {
    animation-name: example;
    animation-duration: 10s;
    animation-iteration-count: infinite;
}

@keyframes example {
    0%{background-color: red;}
    7%{background-color: orangered}
    14%{background-color: orange}
    21%{background-color: #ffc400}
    28%{background-color: yellow;}
    32%{background-color: yellowgreen}
    42%{background-color: green}
    49%{background-color: #00ffdd}
    56%{background-color: lightblue}
    70%{background-color: blue}
    84%{background-color: purple}
    91%{background-color: #ff00d4}
    100%{background-color: red}
}

a{
    animation-name: example1;
    animation-duration: 10s;
    animation-iteration-count: infinite;
}

@keyframes example1 {
    0%{color: green}
    7%{color: #00ffdd}
    14%{color: lightblue}
    21%{color: blue}
    28%{color: purple}
    32%{color: #ff00d4}
    42%{color: red}
    49%{color: orangered}
    56%{color: orange}
    70%{color: #ffc400}
    84%{color: yellow;}
    91%{color: yellowgreen}
    100%{color: green}
}