function couleur(o, c, t) {
 o.t[n] = setTimeout(function() {
  o.style.color = "rgb(" + c + ", " + c + ", " + c + ")";
 }, t);
}
function effet(o) {
 if(o.t) {
  for(n = 0; n <= 16; n++) {
   clearTimeout(o.t[n]);
  }
 } else {
  o.t = new Array();
 }
 for(n = 0; n <= 16; n++) {
  var c = Math.round(Math.cos(n * Math.PI / 8) * 127 + 127);
  couleur(o, c, 50 * n);
 }
}