$color-alpha: #000;

$list-alpha: 
  rgba(#fff, .5),
  #2ecc71, 
  #27ae60,
  #f1c40f,
  #f39c12,
  #3498db,
  #2980b9,
  #e74c3c,
  #c0392b,
  #9b59b6,
  #8e44ad, 
  #1abc9c,
  #16a085
;

$unit-alpha: length($list-alpha);
$unit-beta: .5s;
$unit-gamma: 100% / ($unit-alpha);

article {
  @extend %center;
}

.candybox2 {
  font-weight: bold;
  
  span {
    @for $i from 1 through $unit-alpha {
      &:nth-child(#{$unit-alpha}n+#{$i}) {
        @include animation(candy linear $unit-beta infinite forwards (-$unit-beta / $unit-alpha * $i));
      }
    }
  }
}

@include keyframes(candy) {
    @for $i from 1 through ($unit-alpha + 1) {
      #{$unit-gamma * ($i - 1)} {
        color: darken(nth($list-alpha, ($i % $unit-alpha) + 1), 15%);
        text-shadow: 
          .1em 0 .1em nth($list-alpha, ($i % $unit-alpha) + 1),
   .15em 0 .1em nth($list-alpha, ($i % $unit-alpha) + 1)
        ;
      }
    }
}