macOS Under Page Background

NSColor.underPageBackgroundColor

Window & Surface Canvas

Adaptive System Token•macOS 10.10+ / 10.14+, AppKit

Complete technical specification and developer reference for Under Page Background in Apple's macOS design system. In light appearance, it resolves to HEX rgba(150, 150, 150, 0.9); in dark appearance, it dynamically adapts to HEX #282828. Features wide-gamut Display P3 values, UIKit bridge (UIColor.underPageBackgroundColor), AppKit bridge (NSColor.underPageBackgroundColor), WCAG contrast audit, and Xcode drop-in initializers.

Light Modergba(150, 150, 150, 0.9)

Dark Mode#282828

Under Page Background Color Preview

The background behind a document's content.

ColorNSColor.underPageBackgroundColor

Copy:

Dynamic Asset

Window & Surface Canvas

macOS 10.10+ / 10.14+, AppKit

Initializers & Color Spaces

Color(r:g:b:)Color(red: 0.588, green: 0.588, blue: 0.588)

Color(r:g:b:op:)Color(red: 0.588, green: 0.588, blue: 0.588, opacity: 0.90)

Color(hue:sat:bri:)HSBColor(hue: 0.000, saturation: 0.000, brightness: 0.588, opacity: 0.90)

Color(.displayP3)Wide GamutColor(.displayP3, red: 0.588, green: 0.588, blue: 0.588, opacity: 0.90)

Color(.sRGB)Color(.sRGB, red: 0.588, green: 0.588, blue: 0.588, opacity: 0.90)

Color(hex:)ExtensionColor(hex: "rgba(150, 150, 150, 0.9)")

#colorLiteralXcode#colorLiteral(red: 0.588, green: 0.588, blue: 0.588, alpha: 0.90)

Color(uiColor:)iOSColor(uiColor: UIColor(red: 0.588, green: 0.588, blue: 0.588, alpha: 0.90))

Active HEX: rgba(150, 150, 150, 0.9)P3 R: 0.588 G: 0.588 B: 0.588

Technical Color Specifications

Exact resolved HEX codes, sRGB 8-bit components, HSL, and normalized Swift floating-point decimals for Light and Dark modes.

Color Metric / Space	Light Appearance	Dark Appearance	Swift Code Literal
HEX Code	rgba(150, 150, 150, 0.9)	#282828	Color(hex: "rgba(150, 150, 150, 0.9)")
sRGB (0–255)	rgba(150, 150, 150, 0.9)	rgb(40, 40, 40)	(r: 0.588, g: 0.588, b: 0.588)
Display P3 (Wide Gamut)	P3 (0.588, 0.588, 0.588)	P3 (0.157, 0.157, 0.157)	Color(.displayP3, ...)
HSL / HSB	hsla(0, 0%, 59%, 0.9)	hsl(0, 0%, 16%)	Color(hue:sat:bri:)
Platform Bridge	UIKit: `UIColor.underPageBackgroundColor`	AppKit: `NSColor.underPageBackgroundColor`	Color(uiColor:) / Color(nsColor:)

Light Appearance

Light Theme

HEX Code

rgba(150, 150, 150, 0.9)

RGB (0–255)

rgba(150, 150, 150, 0.9)

HSL

hsla(0, 0%, 59%, 0.9)

Normalized Swift Literal:

(r: 0.588, g: 0.588, b: 0.588)

Dark Appearance

Dark Theme

HEX Code

#282828

RGB (0–255)

rgb(40, 40, 40)

HSL

hsl(0, 0%, 16%)

Normalized Swift Literal:

(r: 0.157, g: 0.157, b: 0.157)

Drop-In Developer Snippets

Ready-to-paste code blocks for Xcode asset catalogs and Swift files.

Xcode Location: Save as Contents.json inside Assets.xcassets/Under Page Background.colorset/

Includes Light + Dark Modes

Contents.json

{
  "colors": [
    {
      "color": {
        "color-space": "srgb",
        "components": {
          "red": "0.588",
          "green": "0.588",
          "blue": "0.588",
          "alpha": "0.900"
        }
      },
      "idiom": "universal"
    },
    {
      "appearances": [
        {
          "appearance": "luminosity",
          "value": "dark"
        }
      ],
      "color": {
        "color-space": "srgb",
        "components": {
          "red": "0.157",
          "green": "0.157",
          "blue": "0.157",
          "alpha": "1.000"
        }
      },
      "idiom": "universal"
    }
  ],
  "info": {
    "author": "xcode",
    "version": 1
  }
}

Live UI Component Sandbox

Preview Color.under page background inside standard Apple interface components.

Interactive Controls

Active TagBadge 99+

Toggle Tint

Container & Typography Styling

●SwiftUI Notification

Just now

Demonstrates how Apple designers pair system background tints with dynamic Under Page Background accents.

Dynamic Headline in Under Page Background

.foregroundStyle(NSColor.underPageBackgroundColor)

Platform Implementation Snippets

Ready-to-use Swift code for SwiftUI, UIKit, and AppKit applications.

AppKit (macOS Swift)

// AppKit (macOS)
let button = NSButton()
button.contentTintColor = NSColor.underPageBackgroundColor

// Custom Layer Tint
let layer = CALayer()
layer.backgroundColor = NSColor.underPageBackgroundColor.cgColor

// Bridging AppKit into SwiftUI
let swiftUIColor = Color(nsColor: .underPageBackgroundColor)

WCAG 2.1 Accessibility Contrast Audit

Contrast calculations of Under Page Background against pure white and iOS OLED dark surfaces.

Light Mode (rgba(150, 150, 150, 0.9))on White (#FFF)

Contrast Ratio:2.58:1

Normal Text (4.5:1 AA): Fail

Dark Mode (#282828)on Dark (#1C1C1E)

Contrast Ratio:1.15:1

Normal Text (4.5:1 AA): Fail

Recommended HIG Use Cases

Standard NSWindow background canvas
Document scroll view wells and split view panes
Inspector sidebars and toolbar panels

Anti-Patterns to Avoid

Foreground text content
Hairline icon strokes

Browse More macOS Colors

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Frequently Asked Questions

How do I use NSColor.underPageBackgroundColor in macOS AppKit apps?

In AppKit, assign NSColor.underPageBackgroundColor to NSView, NSTextField, or NSButton styling. In SwiftUI on macOS, bridge it using Color(nsColor: .underPageBackgroundColor).

What is the HEX code for macOS Under Page Background in light and dark mode?

In light appearance, Under Page Background resolves to rgba(150, 150, 150, 0.9). In dark appearance, it automatically adapts to #282828.

How do I bridge NSColor.underPageBackgroundColor into SwiftUI?

In SwiftUI views on macOS, instantiate Color(nsColor: .underPageBackgroundColor) to access the native AppKit dynamic color token.

Does Under Page Background adapt to Dark Mode and vibrancy in macOS?

Yes, NSColor.underPageBackgroundColor is an appearance-aware NSColor that updates automatically when switching between light and dark modes or across vibrant desktop materials.

Why use AppKit system colors instead of hardcoded hex values?

NSColor system tokens adapt automatically to user accent color preferences, Dark Mode, and accessibility contrast settings.