/material-3

name: material-3
description: >
  Implement Google's Material Design 3 (Material You) UI system. Primary: Jetpack Compose
  Material3 (MaterialTheme, components, adaptive layout). Also Flutter and limited web
  (@material/web, maintenance mode). Covers tokens, 30+ components, layout, theming,
  M3 Expressive (platform matrix), and accessibility. Use when: "material design", "MD3",
  "material you", "Jetpack Compose", "MaterialTheme", "material component", "md3 button".
user-invokable: true
argument-hint: "[component|theme|layout|scaffold|audit] [description or URL]"

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.

Current Updates: Google I/O 2026

Material's [Google I/O 2026 update](https://m3.material.io/blog/whats-new-at-io26) reinforces a **Compose-first** Android path and expands expressive/adaptive guidance:

• **Material Android is Compose-first**: For new Android work, prefer Jetpack Compose Material3 for the latest components, expressive APIs, adaptive scaffolds, and Styles API integration. Android Views may remain necessary in existing apps, but they should not be treated as the default path for new Material 3 implementations.
• **Expressive layout system**: Use an expressive layout scaffold to adapt screens across mobile, desktop, foldables, watches, XR, and other spatial form factors. Start from adaptive scaffolds/window size classes instead of fixed phone-first layouts.
• **8dp spacing system**: Apply spacing tokens for margins, padding, and gaps so layouts and components can adapt programmatically to device type and density.
• **New/updated expressive components**: Lists, menus, search, and search app bars have refreshed expressive guidance, with Jetpack Compose as the primary implementation target.
• **Watches and XR**: Watches emphasize physics-based motion, arc text, and edge-hugging containers. XR emphasizes spatial panels and depth-based elevation.

**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?**

Jetpack Compose          → Primary: androidx.compose.material3, MaterialTheme, references/*
Flutter                  → useMaterial3: true in ThemeData, ColorScheme.fromSeed()
Web (vanilla JS)         → @material/web (limited; maintenance mode) + CSS custom properties
Web (React/Vue/Svelte)   → CSS custom properties + wrapper components (no official React lib)
Web (CSS-only)           → MD3 token values as CSS custom properties (no <md-*> elements)

Design Token System

All MD3 tokens use the `md.sys` namespace. **Jetpack Compose** maps roles to `MaterialTheme.colorScheme`, `MaterialTheme.typography`, and `MaterialTheme.shapes` (same semantic roles as the spec). **On the web**, these map to CSS custom properties (`--md-sys-*`):

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` | Con