Incrementing color SCSS mixin. Pass in a number count to loop and a color to increment. However you decide to increment (darker, lighter, opaque, etc) is up to you. Example shows incrementing an anchor in a list item receiving a darker background color.

incrementing-color.scss

@mixin bgColor($count, $color) {
  $loop_color: $color;
  
  @for $i from 0 through $count {
    $loop_color: shade($loop_color, 8%);
    
    li:nth-of-type(#{$i}) > a {
      background-color: $loop_color;
    }
    
  }
  
}