$colors:
  hsla(337, 84, 48, 0.75)
  hsla(160, 50, 48, 0.75)
  hsla(190, 61, 65, 0.75)
  hsla( 41, 82, 52, 0.75);
$size: 2.5em;
$thickness: 0.5em;

// Calculated variables.
$lat: ($size - $thickness) / 2;
$offset: $lat - $thickness;

.loader {
  position: relative;
  width: $size;
  height: $size;
  transform: rotate(165deg);
  
  &:before,
  &:after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    display: block;
    width: $thickness;
    height: $thickness;
    border-radius: $thickness / 2;
    transform: translate(-50%, -50%);
  }
  
  &:before {
    animation: before 2s infinite;
  }
  
  &:after {
    animation: after 2s infinite;
  }
}

@keyframes before {
  0% {
    width: $thickness;
    box-shadow:
      $lat (-$offset) nth($colors, 1),
      (-$lat) $offset nth($colors, 3);
  }
  35% {
    width: $size;
    box-shadow:
      0 (-$offset) nth($colors, 1),
      0   $offset  nth($colors, 3);
  }
  70% {
    width: $thickness;
    box-shadow:
      (-$lat) (-$offset) nth($colors, 1),
      $lat $offset nth($colors, 3);
  }
  100% {
    box-shadow:
      $lat (-$offset) nth($colors, 1),
      (-$lat) $offset nth($colors, 3);
  }
}

@keyframes after {
  0% {
    height: $thickness;
    box-shadow:
      $offset $lat nth($colors, 2),
      (-$offset) (-$lat) nth($colors, 4);
  }
  35% {
    height: $size;
    box-shadow:
        $offset  0 nth($colors, 2),
      (-$offset) 0 nth($colors, 4);
  }
  70% {
    height: $thickness;
    box-shadow:
      $offset (-$lat) nth($colors, 2),
      (-$offset) $lat nth($colors, 4);
  }
  100% {
    box-shadow:
      $offset $lat nth($colors, 2),
      (-$offset) (-$lat) nth($colors, 4);
  }
}



/**
 * Attempt to center the whole thing!
 */

html,
body {
  height: 100%;
}

.loader {
  position: absolute;
  top: calc(50% - #{$size / 2});
  left: calc(50% - #{$size / 2});
}