colors.css

* {
    animation-name: colors;
    animation-duration: 4s;
    animation-iteration-count: infinite;
}

@keyframes colors {
    0% { text-shadow: 0 0 1pt hsl(0, 100%, 50%); }
    17% { text-shadow: 0 0 1pt hsl(60, 100%, 50%); }
    33% { text-shadow: 0 0 1pt hsl(120, 100%, 50%); }
    50% { text-shadow: 0 0 1pt hsl(180, 100%, 50%); }
    66% { text-shadow: 0 0 1pt hsl(240, 100%, 50%); }
    83% { text-shadow: 0 0 1pt hsl(300, 100%, 50%); }
    100% { text-shadow: 0 0 1pt hsl(360, 100%, 50%); }
}