$ct-series-names: () !default;
$ct-series-colors: () !default;

@function setColor($color) {
   @if (lightness($color) > 40) {
      @return darken($color, 30%);
    }
    @else {
      @return lighten($color, 30%);
    }
}

@for $i from 0 to length($ct-series-names) {
   $color: nth($ct-series-colors, $i + 1);

   .ct-series-#{nth($ct-series-names, $i + 1)} {
      .ct-point, .ct-line, .ct-bar, .ct-slice-donut {
         stroke: $color;
      }

      .ct-bar + .ct-barlabel {
         fill: setColor($color);
      }

      .ct-circle {
         fill: $color;

         & + .ct-label {
            fill: $color;
         }
      }

      .ct-slice-pie, .ct-area, .ct-slice-donut-solid {
         fill: $color;
         stroke: setColor($color);
      }
   }

   // legend
   .ct-series-#{$i}:before {
      background-color: $color;
      border-color: $color;
   }
}