Material Design 3

This skill guides implementation of Google's Material Design 3 (MD3) — a personal, adaptive, expressive design system. MD3 uses dynamic color, tonal surfaces, rounded shapes, and spring-based motion to create UIs that feel alive and personal.

Philosophy

MD3 is built on three principles:

• Personal: Dynamic color adapts UI to the user's wallpaper or content. Theming is individual, not one-size-fits-all.
• Adaptive: Layouts transform across 5 window size classes. Components resize, reposition, and change form factor responsively.
• Expressive: Shape morphing, spring physics, and emphasized typography create moments of delight without sacrificing usability.

Key differences from MD2:

• Tonal surfaces replace elevation shadows as the primary depth cue
• Dynamic color generates full schemes from a single seed color
• Fully rounded corners by default (not slightly rounded)
• Spring-based motion physics replace fixed easing curves for components
• 3 levels of user-controlled contrast (standard/medium/high)

Relationship with frontend-design skill: When both skills are active, MD3 provides the design system (tokens, components, layout rules) and frontend-design provides creative direction within those constraints. MD3 rules take precedence for component structure and token usage. Note: Roboto/Roboto Flex IS the correct default typeface in MD3 — the frontend-design guidance to avoid Roboto does not apply when implementing MD3.

Decision Tree

What are you building?

Full app scaffold        → See "Common Patterns: App Shell" + references/layout-and-responsive.md
Single component         → See "Component Quick Reference" table → references/component-catalog.md
Custom theme             → See references/theming-and-dynamic-color.md
Form / input layout      → See references/component-catalog.md § Input Components
Navigation structure     → See references/navigation-patterns.md
Data display             → See references/component-catalog.md § Data Display

What platform?

Web (vanilla JS)         → @material/web components + CSS custom properties
Web (React/Vue/Svelte)   → CSS custom properties + wrapper components (no official React lib)
Web (CSS-only)           → Use MD3 token values as CSS custom properties (no <md-*> elements)
Flutter                  → material3: true in ThemeData, ColorScheme.fromSeed()
Jetpack Compose          → MaterialTheme with Material3 dependencies

Design Token System

All MD3 tokens use the md.sys namespace. On the web, these map to CSS custom properties:

Color Tokens (--md-sys-color-*)

Token	Purpose
primary	High-emphasis fills, text, icons against surface
on-primary	Text/icons on primary
primary-container	Standout fill for key components (FAB, etc.)
on-primary-container	Text/icons on primary-container
secondary / on-secondary	Less prominent accents
secondary-container / on-secondary-container	Recessive components (tonal buttons)
tertiary / on-tertiary	Contrasting accents
tertiary-container / on-tertiary-container	Complementary containers
error / on-error	Error states (static — doesn't change with dynamic color)
error-container / on-error-container	Error container fills
surface	Default background
on-surface	Text/icons on any surface
on-surface-variant	Lower-emphasis text/icons on surface
surface-container-lowest	Lowest-emphasis container
surface-container-low	Low-emphasis container
surface-container	Default container (nav areas)
surface-container-high	High-emphasis container
surface-container-highest	Highest-emphasis container
surface-dim / surface-bright	Maintain relative brightness across light/dark
inverse-surface / inverse-on-surface / inverse-primary	Contrasting elements (snackbars)
outline	Important boundaries (text field borders)
outline-variant	Decorative elements (dividers)

Full details: references/color-system.md

Typography Tokens (--md-sys-typescale-*)

Scale	Sizes	Use
Display	L / M / S	Hero text, large numbers
Headline	L / M / S	Section headers
Title	L / M / S	Smaller headers, card titles
Body	L / M / S	Paragraph text, descriptions
Label	L / M / S	Buttons, chips, captions

Each style has tokens for: -font, -weight, -size, -line-height, -tracking Plus 15 emphasized variants (higher weight) via --md-sys-typescale-emphasized-*

Full details: references/typography-and-shape.md

Shape Tokens (--md-sys-shape-corner-*)

Token	Value	Example components
none	0dp	—
extra-small	4dp	Chips, snackbars
small	8dp	Text fields, menus
medium	12dp	Cards, dialogs
large	16dp	FABs, navigation drawer
large-increased	20dp	(Expressive)
extra-large	28dp	Bottom sheets
extra-large-increased	32dp	(Expressive)
extra-extra-large	48dp	(Expressive)
full	9999px	Buttons, chips, badges

Elevation Levels

Level	DP	Tonal offset	Use
0	0dp	None	Flat surfaces, most components at rest
1	1dp	+5% primary	Elevated cards, modal sheets
2	3dp	+8% primary	Menus, nav bar, scrolled app bar
3	6dp	+11% primary	FAB, dialogs, search, date/time pickers
4	8dp	+12% primary	(hover/focus increase only)
5	12dp	+14% primary	(hover/focus increase only)

Elevation in MD3 is communicated through tonal surface color, not shadows. Shadows are only used when needed for additional protection against busy backgrounds.

Motion

MD3 Expressive (May 2025) introduced spring-based motion physics for components. The legacy easing/duration system is still used for transitions (enter/exit/shared-axis):

Easing	Duration	Transition type
Emphasized	500ms	Begin and end on screen
Emphasized decelerate	400ms	Enter the screen
Emphasized accelerate	200ms	Exit the screen
Standard	300ms	Begin and end on screen (utility)
Standard decelerate	250ms	Enter screen (utility)
Standard accelerate	200ms	Exit screen (utility)

CSS easing values:

• Emphasized: cubic-bezier(0.2, 0, 0, 1)
• Emphasized decelerate: cubic-bezier(0.05, 0.7, 0.1, 1)
• Emphasized accelerate: cubic-bezier(0.3, 0, 0.8, 0.15)
• Standard: cubic-bezier(0.2, 0, 0, 1)
• Standard decelerate: cubic-bezier(0, 0, 0, 1)
• Standard accelerate: cubic-bezier(0.3, 0, 1, 1)

Component Quick Reference

Category	Components (web element examples)
Actions	Button (filled / outlined / text / elevated / tonal), Button group, FAB, Extended FAB, FAB menu, Icon button, Segmented button, Split button
Communication	Badge, Loading indicator, Progress indicator (linear / circular), Snackbar, Tooltip
Containment	Card (filled / outlined / elevated), Carousel, Dialog, Bottom sheet, Side sheet, Divider
Input	Checkbox, Chips (assist / filter / input / suggestion), Date picker, Menu, Radio button, Slider, Switch, Text field, Time picker
Navigation	App bar, Navigation bar, Navigation drawer, Navigation rail, Search, Tabs, Toolbar
Data Display	List

For exact web element names (md-filled-button, md-outlined-text-field, etc.), variants, attributes, a11y notes, and code examples for each component, see references/component-catalog.md. Components not implemented in @material/web are documented there with CSS-only fallbacks.

Web Implementation

Use @material/web Web Components for vanilla JS, or CSS custom properties with standard HTML for CSS-only setups. Full setup, imports, basic-usage example, theming via --md-sys-color-* custom properties, component-level overrides, and the dark-theme media query are in references/web-implementation.md. Theming details continue in references/theming-and-dynamic-color.md.

Common Patterns

Code examples for the canonical MD3 screen-level layouts — app shell (responsive nav rail + top app bar + content), card grid, form layout — live in references/common-patterns.md. More layout patterns continue in references/navigation-patterns.md and references/layout-and-responsive.md.

Anti-Patterns

Never do these when implementing MD3:

• Mix MD2 and MD3 libraries: Don't use @material/mdc-* (MD2) alongside @material/web (MD3). They have incompatible APIs and styling.
• Hardcode colors: Always use var(--md-sys-color-*) tokens, never raw hex/rgb values. Hardcoded colors break dynamic theming, dark mode, and contrast adjustment.
• Ignore tonal pairing: Only combine colors in their intended pairs (e.g., primary + on-primary, surface-container + on-surface). Arbitrary pairings break contrast in dynamic color and high contrast modes.
• Use outline for dividers: Use outline-variant for dividers. outline is for important boundaries like text field borders.
• Import all of @material/web: Always import individual component modules. Barrel imports include every component and destroy bundle size.
• Use border-radius directly: Use shape tokens (var(--md-sys-shape-corner-medium)) so shapes stay consistent with theming.
• Use shadows for elevation by default: MD3 communicates elevation through tonal surface color, not shadows. Only add shadows when elements need extra separation from busy backgrounds.
• Apply frontend-design "avoid Roboto" rule: Roboto Flex is the intended MD3 typeface. It's correct here. Replace it only if intentionally customizing the type scale.
• Assume SSR compatibility: @material/web uses Web Components (custom elements) which require JavaScript to render. They won't produce meaningful HTML in SSR without additional hydration strategies.
• Ignore foldables and large screens: MD3 is designed for all screen sizes. Don't ship phone-only layouts — use canonical layouts, multi-pane at 600dp+, and test on foldable/tablet emulators. Place no interactive content across the fold/hinge.
• Stretch content to fill wide screens: On Large (1200dp+) and Extra-large (1600dp+) windows, constrain content to a max width (840–1040dp). Endless-width text lines are unreadable.

Platform Notes

Flutter

MaterialApp(
  theme: ThemeData(
    useMaterial3: true,
    colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
  ),
);

Jetpack Compose

MaterialTheme(
    colorScheme = dynamicLightColorScheme(context), // or dynamicDarkColorScheme
    typography = Typography(),
    shapes = Shapes(),
) {
    // Content
}

Component Name Mapping

Concept	Web	Flutter	Compose
Filled button	md-filled-button	FilledButton	Button
Outlined text field	md-outlined-text-field	OutlinedTextField	OutlinedTextField
FAB	md-fab	FloatingActionButton	FloatingActionButton
Navigation bar	md-navigation-bar	NavigationBar	NavigationBar
Switch	md-switch	Switch	Switch

M3 Expressive (May 2025)

The Expressive update adds visual richness while maintaining usability:

• Spring-based motion: Components now use spring physics instead of fixed easing curves. More natural and responsive. (Easing/duration still used for transitions.)
• Emphasized typography: 15 new emphasized type styles for selection states, actions, and headlines. Higher weight than baseline.
• Shape morphing: Components can morph between shapes on interaction (press, select). Currently Compose-only; web unavailable.
• New button sizes: XS, S (default), M, L, XL with toggle (selection) support.
• New corner radii: large-increased (20dp), extra-large-increased (32dp), extra-extra-large (48dp).
• 3 contrast levels: Standard, medium, and high contrast — user-controlled.

When targeting web, note that many Expressive features (shape morph, spring physics) aren't yet available in @material/web. Use the CSS easing/duration tokens as fallback.

MD3 Compliance Audit

When invoked with audit as the argument (e.g., /material-3 audit), or when asked to audit/review MD3 compliance, analyze the target app or page and produce a compliance report.

Audit Procedure

1. Identify the target: The user provides a URL (use browser tools to inspect), file paths (read source), or a running app.
2. Inspect the following categories and score each 0–10:

Category	What to check
Color tokens	Uses --md-sys-color-* tokens (not hardcoded hex). Proper tonal pairing (on-X with X). Dark mode support. No arbitrary color combinations that break contrast.
Typography	Uses MD3 type scale tokens. Correct scale usage (Display for heroes, Body for text, Label for buttons). Consistent font family.
Shape	Uses shape tokens for border-radius. Correct token per component (full for buttons, medium for cards). No raw pixel values.
Elevation	Tonal surface colors used instead of shadows. Correct elevation levels per component. Hover/focus raises by 1 level.
Components	Uses @material/web elements or correctly implements MD3 component specs. Correct variants for context. Proper slot usage.
Layout	Responsive breakpoints match MD3 (compact/medium/expanded/large/extra-large). Uses canonical layouts where appropriate. Proper margins and spacing. Multi-pane layouts on medium+ screens. Content constrained to readable widths on large screens. Foldable hinge avoidance if targeting foldables.
Navigation	Correct nav component for screen size (bar on mobile, rail on tablet, drawer on desktop). Responsive transitions. Hover states for pointer devices on large screens.
Motion	Transitions use MD3 easing/duration tokens. Appropriate easing type for transition direction (enter/exit/persist).
Accessibility	Color contrast meets 3:1 minimum (MD3 built-in). Proper ARIA labels. Keyboard navigation. Focus indicators.
Theming	Theme is applied via CSS custom properties. Supports dark mode. Dynamic color ready (tokens not hardcoded). Component-level overrides use proper token names.

3. Generate the report:

# MD3 Compliance Audit Report

Target: [URL or file path]
Date: [date]
Overall Score: [X/100]

## Scores by Category
| Category       | Score | Status |
|----------------|-------|--------|
| Color tokens   | X/10  | [pass/warn/fail] |
| Typography     | X/10  | [pass/warn/fail] |
| Shape          | X/10  | [pass/warn/fail] |
| Elevation      | X/10  | [pass/warn/fail] |
| Components     | X/10  | [pass/warn/fail] |
| Layout         | X/10  | [pass/warn/fail] |
| Navigation     | X/10  | [pass/warn/fail] |
| Motion         | X/10  | [pass/warn/fail] |
| Accessibility  | X/10  | [pass/warn/fail] |
| Theming        | X/10  | [pass/warn/fail] |

## Critical Issues
[List items scoring 0-3 with specific file:line references and fixes]

## Warnings
[List items scoring 4-6 with recommendations]

## Passing
[List items scoring 7-10 with notes on what's done well]

## Recommended Fixes (Priority Order)
1. [Most impactful fix first]
2. ...

Audit Methods

For a live URL (browser tools available):

• Navigate to the page with mcp__claude-in-chrome__navigate
• Read the page DOM with mcp__claude-in-chrome__read_page
• Extract CSS custom properties with mcp__claude-in-chrome__javascript_tool
• Check computed styles for MD3 token usage
• Test responsive behavior by resizing with mcp__claude-in-chrome__resize_window
• Screenshot at different breakpoints

For source code (file paths provided):

• Read HTML/JSX/template files for component usage
• Read CSS/SCSS files for token usage and hardcoded values
• Check imports for @material/web components
• Search for hardcoded colors, border-radius values, box-shadows
• Verify responsive breakpoints in media queries

Quick checks (grep patterns for common violations):

# Hardcoded colors (should use tokens)
grep -rn '#[0-9a-fA-F]\{3,8\}' --include='*.css' --include='*.scss'
grep -rn 'rgb\(|rgba\(' --include='*.css' --include='*.scss'

# Raw border-radius (should use shape tokens)
grep -rn 'border-radius:' --include='*.css' | grep -v 'var(--md-sys-shape'

# Raw box-shadow (MD3 uses tonal elevation)
grep -rn 'box-shadow:' --include='*.css'

# MD2 imports (should be @material/web)
grep -rn '@material/mdc-' --include='*.js' --include='*.ts'

# Missing dark mode
grep -rn 'prefers-color-scheme' --include='*.css'

Scoring Guide

• 9-10: Fully MD3 compliant, uses correct tokens and patterns
• 7-8: Mostly compliant, minor issues (e.g., a few hardcoded values)
• 4-6: Partially compliant, some MD3 patterns but significant gaps
• 1-3: Major violations, mostly non-MD3 or MD2 patterns
• 0: Not applicable or completely absent

Status thresholds: pass (7+), warn (4-6), fail (0-3)

Reference Documents

• references/color-system.md — Complete color role catalog, tonal palettes, dynamic color, light/dark scheme mapping
• references/typography-and-shape.md — Type scale values, shape corner scale, elevation levels, motion tokens
• references/component-catalog.md — All 30+ components with web element names, attributes, code examples, a11y notes
• references/navigation-patterns.md — Which navigation component to use, responsive nav transitions
• references/layout-and-responsive.md — Breakpoints, canonical layouts, CSS Grid implementation
• references/theming-and-dynamic-color.md — Theme generation, brand color integration, dark mode, runtime switching