$golden-ratio: 1.61803398875;

@function explorer-size($exponent) {
  $value: $golden-ratio;

  @if $exponent > 0 {
    @for $i from 1 through $exponent {
      $value: $value * $golden-ratio;
    }
  } @elseif $exponent < 0 {
    @for $i from 1 through -$exponent {
      $value: $value / $golden-ratio;
    }
  }

  @return 1rem * $value;
}