:root {

@for $level from 1 through 12 {
  @if $level % 4 == 0 {
    --toc-#{$level}: #{darken($theme-white, 4 * 8.8%)};
  } @else {
    --toc-#{$level}: #{darken($theme-white, $level % 4 * 8.8%)};
  }
}

}