[рони]

Блондинка,

var spans = document.querySelectorAll('.colon');
var colons = ["hsl(0, 0%, 54%)", "hsl(0, 0%, 48%)", "hsl(0, 0%, 42%)", "hsl(0, 0%, 36%)", "hsl(0, 0%, 30%)", "hsl(0, 0%, 24%)", "hsl(0, 0%, 18%)", "hsl(0, 0%, 12%)", "hsl(0, 0%, 6%)", "hsl(0, 0%, 0%)"];
var op = [.2, .4, .6, .8, 1, 1, .8, .6, .4, .2];
step = 0;
(function color() {
    spans.forEach(function(elem) {
        elem.style.color = colons[step];
        elem.style.opacity = op[step];
    });
    step = ++step % colons.length;
    setTimeout(color, 200);
})()