ColorConstants and SunConstants

ColorConstants and SunConstants (both from scenerystack/sun) are small plain-object modules of shared default values reused across scenerystack/sun components — mainly so a handful of default colors and magic numbers exist in exactly one place rather than being copy-pasted into every button/slider/spinner that needs them. Neither is a class; both are readonly-style constant objects you read values from directly.

import { ColorConstants, SunConstants } from 'scenerystack/sun';
import { RectangularPushButton } from 'scenerystack/sun';

// Matches the default look of PhET's boxed buttons/radio buttons
const button = new RectangularPushButton( {
  baseColor: ColorConstants.LIGHT_BLUE
} );

console.log( SunConstants.VALUE_NAMED_PLACEHOLDER ); // '{{value}}'

ColorConstants

Constant	Value	Used for
LIGHT_BLUE	new Color( 153, 206, 255 )	The default baseColor for most scenerystack/sun buttons, including RectangularRadioButton
LIGHT_GRAY	new Color( 220, 220, 220 )	The conventional "disabled" fill color used in several components

Both are Color instances (from scenerystack/scenery), so they support the usual Color methods (brighterColor, darkerColor, withAlpha, …) if you want a variant rather than the exact default.

SunConstants

Constant	Value	Used for
VALUE_NAMED_PLACEHOLDER	''	The named placeholder convention for value-substitution string patterns (used with StringUtils.fillIn), e.g. in a NumberDisplay's format string
VALUE_NUMBERED_PLACEHOLDER	'{0}'	The older numbered-placeholder convention (used with StringUtils.format); deprecated — prefer named placeholders in new code
SLIDER_VERTICAL_ROTATION	-Math.PI / 2	The rotation angle Slider applies internally to lay out a vertical slider using the same horizontal-authored geometry

These are defaults, not requirements

Nothing forces you to use ColorConstants.LIGHT_BLUE or SunConstants.VALUE_NAMED_PLACEHOLDER — components fall back to them only when you don't supply your own baseColor/format string. They're documented here mainly so custom components can match PhET's conventional look-and-feel intentionally, rather than by guessing at hardcoded hex values.