SCSS

Background cascade

@mixin background ($title, $color) {
  $i: 0;
  @each $bg in (
    zero darken($color, 15%),
    one $color,
    two  lighten($color, 10%),
    three lighten($color, 15%),
    four lighten($color, 20%),
    five lighten($color, 25%)
  ) {
    .background--#{$title}_#{$i} {
      background: #{nth($bg, 2)}
    }
    $i: $i + 1;
  }
}