styles.less

// http://codepen.io/Bidji/pen/dPEzwq

.anim-rainbow-color(@delay: 0s) {
  animation: rainbow-color-keyframes 0.6s @delay linear infinite;
}

@keyframes rainbow-color-keyframes {
  0% {
    color: #0057B8;
  }
  20% {
    color: #F11E4A;
  }
  40% {
    color: #F8A527;
  }
  60% {
    color: #266D7F;
  }
  80% {
    color: #82A;
  }
  100% {
    color: #0057B8;
  }
}

.rainbow {
  span:nth-child(1) { .anim-rainbow-color(0.1s); }
  span:nth-child(2) { .anim-rainbow-color(0.15s); }
  span:nth-child(3) { .anim-rainbow-color(0.2s); }
  span:nth-child(4) { .anim-rainbow-color(0.25s); }
  span:nth-child(5) { .anim-rainbow-color(0.3s); }
  span:nth-child(6) { .anim-rainbow-color(0.35s); }
  span:nth-child(7) { .anim-rainbow-color(0.4s); }
  span:nth-child(8) { .anim-rainbow-color(0.45s); }
  span:nth-child(9) { .anim-rainbow-color(0.5s); }
  span:nth-child(10) { .anim-rainbow-color(0.55s); }
  span:nth-child(11) { .anim-rainbow-color(0.6s); }
  span:nth-child(12) { .anim-rainbow-color(0.65s); }
  span:nth-child(13) { .anim-rainbow-color(0.7s); }
  span:nth-child(14) { .anim-rainbow-color(0.75s); }
}