message: add ``carbonLightness`` to illustrative color theme
diff: @@ -17,7 +17,8 @@ const DefaultIllustrativeColor = Color(0xEEEEEE);
  const Description = `Assigns an illustrative color that gives every chain a unique color with lighter carbons (inspired by David Goodsell's Molecule of the Month style).`;
  export const IllustrativeColorThemeParams = {
  - ...ChainIdColorThemeParams
  + ...ChainIdColorThemeParams,
  + carbonLightness: PD.Numeric(0.8, { min: -6, max: 6, step: 0.1 })
  };
  export type IllustrativeColorThemeParams = typeof IllustrativeColorThemeParams
  export function getIllustrativeColorThemeParams(ctx: ThemeDataContext) {
  @@ -29,7 +30,7 @@ export function IllustrativeColorTheme(ctx: ThemeDataContext, props: PD.Values<I
  function illustrativeColor(location: Location, typeSymbol: ElementSymbol) {
  const baseColor = chainIdColor(location, false);
  - return typeSymbol === 'C' ? Color.lighten(baseColor, 0.8) : baseColor;
  + return typeSymbol === 'C' ? Color.lighten(baseColor, props.carbonLightness) : baseColor;
  }
  function color(location: Location): Color {
  