Material3

Material Design 3 — KMP / Compose Multiplatform Skill

This skill guides implementation of Google's Material Design 3 (MD3 / Material You) using Jetpack Compose and Compose Multiplatform for KMP projects (Android + Desktop).

Attribution: This skill is adapted from and gives credit to hamen/material-3-skill by Hamen. The original skill covers web and Flutter targets. This KMP edition strips all web/CSS/Flutter patterns and replaces them with pure Compose Multiplatform APIs, adds the audit report system, and extends the reference set for adaptive layout, navigation, and versioning.

Scope: Compose-only. All examples use androidx.compose.material3 APIs — the same API surface is available in KMP commonMain via org.jetbrains.compose.material3:material3 (declared explicitly in libs.versions.toml). No web CSS, no @material/web elements, no Flutter.

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MD3 Philosophy

Principle	What it means in Compose
Personal	Dynamic color from user wallpaper (Android 12+). Static fallback for Desktop.
Adaptive	WindowSizeClass drives layout changes across compact → expanded screens.
Expressive	Spring-based motion, shape morphing, emphasized typography.

Google I/O 2026 Key Updates

• Compose-first on Android: For all new Android work, use androidx.compose.material3.
• Expressive layout scaffold: Design screens to adapt across mobile, desktop, foldables. Use Material3Adaptive scaffold APIs.
• 8dp spacing system: Define spacing as tokens — never scatter raw Dp literals.
• New expressive components: Lists, menus, search, and search app bars have refreshed expressive guidance; check your Material3 BOM for expressive variants.

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Design Token System

All MD3 values come through MaterialTheme. Never hardcode raw values inline.

Token category	Access in Compose
Color	MaterialTheme.colorScheme.*
Typography	MaterialTheme.typography.*
Shape	MaterialTheme.shapes.*
Spacing	Define a Dimens object (no built-in API)

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Decision Tree

What are you building?

Full app scaffold        → AppTheme setup + references/theming-and-dynamic-color.md
Single component         → references/component-catalog.md
Custom color theme       → references/color-system.md
Typography / fonts       → references/typography-and-shape.md
Navigation structure     → references/navigation-patterns.md
Adaptive layout          → references/layout-and-responsive.md

---

Color Token Summary

Full details in references/color-system.md.

Key Roles (Compose token → usage)

Role	Token	Primary Usage
Primary	colorScheme.primary	FAB, key buttons, active states
On Primary	colorScheme.onPrimary	Text/icons on primary
Primary Container	colorScheme.primaryContainer	Tonal buttons, selected chips
On Primary Container	colorScheme.onPrimaryContainer	Text on primary container
Secondary	colorScheme.secondary	Less prominent accents, filters
Secondary Container	colorScheme.secondaryContainer	Recessive fills
Tertiary	colorScheme.tertiary	Contrasting accent sections
Surface	colorScheme.surface	Cards, sheets, menus
Surface Container	colorScheme.surfaceContainer	Navigation areas
On Surface	colorScheme.onSurface	Body text, icons
On Surface Variant	colorScheme.onSurfaceVariant	Placeholder, helper text
Outline	colorScheme.outline	Input borders, dividers
Error	colorScheme.error	Error states

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Typography Token Summary

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

Category	Styles	Usage
Display	L / M / S	Hero text, large numbers
Headline	L / M / S	Screen/section headers
Title	L / M / S	Toolbar titles, card headers
Body	L / M / S	Paragraph text, descriptions
Label	L / M / S	Buttons, chips, captions

// ✅ Always via MaterialTheme
Text("Title", style = MaterialTheme.typography.titleLarge)
Text("Body", style = MaterialTheme.typography.bodyMedium)

// ❌ Never inline
Text("Title", fontSize = 22.sp, fontWeight = FontWeight.Normal)

---

Shape Token Summary

Token	Corner Radius	Typical Components
shapes.extraSmall	4dp	Chips, snackbars
shapes.small	8dp	Text fields, menus
shapes.medium	12dp	Cards
shapes.large	16dp	FABs, nav drawer
shapes.extraLarge	28dp	Dialogs, bottom sheets

---

Elevation

MD3 communicates depth through tonal surface color, not drop shadows.

Level	Compose API	Tonal Offset	Use
0	Elevation.Level0 / 0.dp	None	Flat surfaces at rest
1	Elevation.Level1 / 1.dp	+5% primary	Elevated cards
2	Elevation.Level2 / 3.dp	+8% primary	Menus, nav bar
3	Elevation.Level3 / 6.dp	+11% primary	FAB, dialogs

// Cards respect tonal elevation automatically via surfaceTonalElevation
ElevatedCard(elevation = CardDefaults.elevatedCardElevation(defaultElevation = 6.dp)) { }

---

Motion Summary

Full details in references/typography-and-shape.md §Motion.

Easing	Compose	Usage
Emphasized	CubicBezierEasing(0.2f, 0f, 0f, 1f)	Elements staying on screen
Emphasized Decelerate	CubicBezierEasing(0.05f, 0.7f, 0.1f, 1f)	Entering screen
Emphasized Accelerate	CubicBezierEasing(0.3f, 0f, 0.8f, 0.15f)	Leaving screen
Standard	FastOutSlowInEasing	Utility animations

Standard Durations

Token	Duration	Usage
Short	100–200ms	Icon/color state changes
Medium	300–400ms	Component expand/collapse
Long	400–500ms	Screen-level transitions

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Component Quick Reference

Component	Compose API	Category
Button (Filled)	Button {}	Actions
Button (Tonal)	FilledTonalButton {}	Actions
Button (Outlined)	OutlinedButton {}	Actions
Button (Text)	TextButton {}	Actions
FAB	FloatingActionButton {}	Actions
Extended FAB	ExtendedFloatingActionButton {}	Actions
Icon Button	IconButton {}, FilledIconButton {}	Actions
Segmented Button	SegmentedButton {}	Actions
Card	Card {}, ElevatedCard {}, OutlinedCard {}	Containment
Dialog	AlertDialog {}, Dialog {}	Containment
Bottom Sheet	ModalBottomSheet {}	Sheets
Snackbar	SnackbarHost {}	Communication
Progress	CircularProgressIndicator(), LinearProgressIndicator()	Communication
Badge	BadgedBox {}	Communication
Checkbox	Checkbox()	Input
RadioButton	RadioButton()	Input
Switch	Switch()	Input
Slider	Slider(), RangeSlider()	Input
TextField	TextField(), OutlinedTextField()	Input
Chips	FilterChip, AssistChip, InputChip, SuggestionChip	Input
TopAppBar	TopAppBar, CenterAlignedTopAppBar, LargeTopAppBar	Navigation
Navigation Bar	NavigationBar {}	Navigation
Navigation Rail	NavigationRail {}	Navigation
Navigation Drawer	ModalNavigationDrawer {}	Navigation
Tabs	TabRow {}, ScrollableTabRow {}	Navigation

Full Compose API + examples: references/component-catalog.md

---

AppTheme Setup (Quick Start)

@Composable
fun AppTheme(
    darkTheme: Boolean = isSystemInDarkTheme(),
    // Dynamic color is Android 12+ only — always falls back to static on Desktop
    dynamicColor: Boolean = true,
    content: @Composable () -> Unit
) {
    val colorScheme = when {
        dynamicColor && Build.VERSION.SDK_INT >= Build.VERSION_CODES.S -> {
            val context = LocalContext.current
            if (darkTheme) dynamicDarkColorScheme(context) else dynamicLightColorScheme(context)
        }
        darkTheme -> DarkColorScheme
        else      -> LightColorScheme
    }

    MaterialTheme(
        colorScheme = colorScheme,
        typography  = AppTypography,
        shapes      = AppShapes,
        content     = content
    )
}

For Compose Multiplatform Desktop: Remove Build.VERSION_SDK_INT check and always use LightColorScheme / DarkColorScheme. Dynamic color has no JVM equivalent.

Full theming guide: references/theming-and-dynamic-color.md

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Core Rules

• Never hardcode Color(0xFF...) in composables — always MaterialTheme.colorScheme.*
• Never inline fontSize, fontFamily, fontWeight — always MaterialTheme.typography.*
• Never inline RoundedCornerShape(12.dp) — always MaterialTheme.shapes.*
• Always wrap content in AppTheme at the root — never in individual screens
• Always support dark mode — test every screen with isSystemInDarkTheme()
• Always use Scaffold — it handles topBar, bottomBar, FAB, snackbarHost, padding
• Minimum touch target: 48×48dp for all interactive elements
• Spacing tokens: always multiples of 4dp — define a Dimens object
• For Desktop/JVM: always use static color schemes — no dynamic color API on JVM

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MD3 Compliance Audit

When the user asks for an audit, a compliance check, or passes code / a screen name with the audit argument, run a full MD3 compliance report using the template below.

How to trigger

audit [screen name or paste code here]
audit HomeScreen
audit <paste composable code>
check this screen against material 3
run md3 audit

Audit Process

1. Scan the target — read the provided code or ask the user to paste the composable(s) to audit.
2. Check each category below in order.
3. Output the report using the exact format specified.
4. Offer fixes — for every ❌ or ⚠️, provide the corrected Compose code snippet inline.

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Audit Report Format

Output the report in this exact structure:

╔══════════════════════════════════════════════════════════╗
║          MD3 COMPLIANCE AUDIT — [Screen/File Name]       ║
║          KMP / Compose Multiplatform Edition             ║
╚══════════════════════════════════════════════════════════╝

Score: [X / 10]   Grade: [A / B / C / D / F]

┌─────────────────────────────────────────────────────────┐
│ CATEGORY RESULTS                                        │
└─────────────────────────────────────────────────────────┘

[✅ / ⚠️ / ❌]  COLOR SYSTEM          [PASS / WARN / FAIL]
[✅ / ⚠️ / ❌]  TYPOGRAPHY            [PASS / WARN / FAIL]
[✅ / ⚠️ / ❌]  SHAPE                 [PASS / WARN / FAIL]
[✅ / ⚠️ / ❌]  SPACING               [PASS / WARN / FAIL]
[✅ / ⚠️ / ❌]  ELEVATION             [PASS / WARN / FAIL]
[✅ / ⚠️ / ❌]  COMPONENTS            [PASS / WARN / FAIL]
[✅ / ⚠️ / ❌]  LAYOUT & ADAPTIVE     [PASS / WARN / FAIL]
[✅ / ⚠️ / ❌]  NAVIGATION            [PASS / WARN / FAIL]
[✅ / ⚠️ / ❌]  MOTION & ANIMATION    [PASS / WARN / FAIL]
[✅ / ⚠️ / ❌]  DARK MODE             [PASS / WARN / FAIL]
[✅ / ⚠️ / ❌]  ACCESSIBILITY         [PASS / WARN / FAIL]
[✅ / ⚠️ / ❌]  THEMING SETUP         [PASS / WARN / FAIL]

┌─────────────────────────────────────────────────────────┐
│ FINDINGS                                                │
└─────────────────────────────────────────────────────────┘

[findings listed per category — see check rules below]

┌─────────────────────────────────────────────────────────┐
│ FIXES                                                   │
└─────────────────────────────────────────────────────────┘

[corrected code snippets for every ❌ and ⚠️]

---

Audit Check Rules — Per Category

1. COLOR SYSTEM

Check	Pass condition	Fail condition
No hardcoded colors in composables	MaterialTheme.colorScheme.* used	Color(0xFF…) literal in UI code
No swapped semantic roles	error used for errors only	error used for success/warning
Both schemes defined	LightColorScheme + DarkColorScheme exist	Only one scheme present
Dynamic color has static fallback	if (dynamicColor && SDK >= S) with else branch	Dynamic color used unconditionally
Extended colors use CompositionLocal	LocalExtendedColors pattern	Raw color passed as parameter
Desktop: no dynamic color API	jvmMain uses static scheme	dynamicDarkColorScheme() in jvmMain

2. TYPOGRAPHY

Check	Pass condition	Fail condition
No inline font sizes	MaterialTheme.typography.* used	fontSize = 16.sp inline
No inline font weights	MaterialTheme.typography.* used	fontWeight = FontWeight.Bold inline
Custom font loaded via Res.font.*	Font(Res.font.*) for KMP	Hardcoded path or fontFamily literal
All 15 styles defined if custom typography	Typography(displayLarge = …, labelSmall = …)	Missing styles in custom Typography
Body text uses bodyLarge/bodyMedium	Correct role applied	displayLarge on body copy

3. SHAPE

Check	Pass condition	Fail condition
No inline RoundedCornerShape	MaterialTheme.shapes.* used	RoundedCornerShape(12.dp) inline
Shape token matches component	Cards use shapes.medium, FABs use shapes.extraLarge	FAB with shapes.small
Custom shapes defined in AppShapes	val AppShapes = Shapes(…) in theme	Shape overrides scattered in UI

4. SPACING

Check	Pass condition	Fail condition
Spacing uses Dimens object	Dimens.md, Dimens.lg, etc.	Scattered 16.dp, 24.dp literals
Values are multiples of 4dp	4, 8, 12, 16, 24, 32, 48dp	15.dp, 7.dp, 11.dp literals
Screen margins consistent	Dimens.screenHorizontal used	Mixed margin values per screen

5. ELEVATION

Check	Pass condition	Fail condition
Tonal elevation used	tonalElevation / CardDefaults.elevatedCardElevation()	Modifier.shadow(8.dp) for depth
Shadow used only for busy backgrounds	Rare Modifier.shadow with clear reason	Shadows on all cards for styling

6. COMPONENTS

Check	Pass condition	Fail condition
Only one Button (filled) per section	Single primary action	Multiple filled buttons per section
FAB in Scaffold.floatingActionButton	Scaffold(floatingActionButton = {…})	FAB positioned manually with Box
Scaffold used on every screen	Scaffold {} wraps each screen	No Scaffold, manual layout
AlertDialog for destructive actions	confirmButton + dismissButton both present	No dismiss option on destructive dialog
Lists use ListItem	ListItem(headlineContent = …)	Custom Row replacing ListItem
Buttons use correct emphasis hierarchy	Filled → Tonal → Elevated → Outlined → Text	Multiple filled buttons, no hierarchy

7. LAYOUT & ADAPTIVE

Check	Pass condition	Fail condition
WindowSizeClass used	calculateWindowSizeClass() or currentWindowAdaptiveInfo()	Fixed-width if (isTablet) hack
No hardcoded breakpoints	WindowWidthSizeClass.* enum	if (width > 600.dp) check
Canonical layout pattern used	Feed / List-Detail / Supporting Pane	None of the canonical patterns applied
Edge-to-edge enabled	enableEdgeToEdge() in Activity	Status bar not handled
WindowInsets applied	Modifier.statusBarsPadding() or Scaffold	Content hidden behind system bars
Adaptive API used for list-detail	NavigableListDetailPaneScaffold	Manual Row reimplementing list-detail

8. NAVIGATION

Check	Pass condition	Fail condition
Nav component matches window size	NavigationBar on compact, NavigationRail on medium, drawer on expanded	Bottom nav on tablet
Bottom nav has 3–5 items	Destination count in range	2 or 6+ items in NavigationBar
launchSingleTop = true	Present on all nav clicks	Duplicate back-stack entries possible
saveState + restoreState	Present on nav clicks	Tab scroll position lost
Type-safe routes	@Serializable objects/classes	String literal routes
NavController not in ViewModel	Navigate via UiEffect	navController injected into ViewModel

9. MOTION & ANIMATION

Check	Pass condition	Fail condition
Easing matches direction	Entering: EmphasizedDecelerate, Leaving: EmphasizedAccelerate	Symmetric easing for enter/exit
animate*AsState has label =	label = "colorAnimation" present	Missing label parameter
Duration ≤ 500ms screen, ≤ 300ms component	Within limits	tween(800ms) on a button
Spring for interactions, tween for transitions	spring() on drag/toggle, tween() on nav	tween() on swipe gesture

10. DARK MODE

Check	Pass condition	Fail condition
isSystemInDarkTheme() wired to theme	darkTheme = isSystemInDarkTheme()	Hard-coded darkTheme = false
Both schemes tested	Code has DarkColorScheme defined	Only LightColorScheme present
@Preview(uiMode = UI_MODE_NIGHT_YES) on previews	Both light and dark previews	Only light mode previews

11. ACCESSIBILITY

Check	Pass condition	Fail condition
Touch targets ≥ 48×48dp	Icons/buttons have Modifier.size(48.dp) or larger	Modifier.size(24.dp) as only modifier on clickable
Icon-only buttons have contentDescription	Non-null description	contentDescription = null on icon button
Contrast ratio ≥ 4.5:1 (normal text)	M3 baseline palette used	Custom palette not validated
No color-only state communication	Icon/text also changes state	Only color changes for selected state
Semantic roles applied	Modifier.semantics { role = Role.Button } where needed	Custom clickable without role

12. THEMING SETUP

Check	Pass condition	Fail condition
Single MaterialTheme call at root	AppTheme wraps root composable only	MaterialTheme called in individual screens
AppTheme has darkTheme + dynamicColor params	Both parameters present	Theme has no parameters
AppTypography, AppShapes defined	Separate files in theme/	Defaults used (MaterialTheme() with no args)
Desktop uses expect/actual for theme	rememberColorScheme split across source sets	Android-only dynamic color call in commonMain

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Scoring

Score	Grade	Meaning
10 / 10	A	Full MD3 compliance — production ready
8–9 / 10	B	Minor warnings — good with small fixes
6–7 / 10	C	Several violations — needs attention
4–5 / 10	D	Major issues — significant rework needed
0–3 / 10	F	Critical violations — MD3 not followed

Each category scores 1 point: ✅ PASS = 1pt, ⚠️ WARN = 0.5pt, ❌ FAIL = 0pt. Round to nearest 0.5.

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Reference Files

File	Contents
references/color-system.md	All 29 color roles, light/dark schemes, dynamic color, custom extensions
references/theming-and-dynamic-color.md	AppTheme setup, dynamic color, KMP (Android+Desktop) theme split
references/typography-and-shape.md	Full 15-style type scale, font setup, shape tokens, elevation, motion
references/component-catalog.md	All 30+ components with Compose API + code examples
references/layout-and-responsive.md	WindowSizeClass, adaptive scaffolds, canonical layouts, spacing tokens
references/navigation-patterns.md	NavBar, Rail, Drawer, Tabs — when to use each, Compose wiring

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Dependencies

⚠️ Deprecation: plugin accessor shorthands

The compose.material3, compose.ui, compose.foundation shorthand accessors previously provided by the Compose Multiplatform Gradle plugin are deprecated as of CMP 1.10.0-beta01.

Old (deprecated)	New (explicit libs entry)
implementation(compose.material3)	implementation(libs.compose.material3)
implementation(compose.ui)	implementation(libs.compose.ui)
implementation(compose.foundation)	implementation(libs.compose.foundation)

⚠️ Breaking: material-icons-core is no longer transitive (since CMP 1.8.2)

Starting with CMP 1.8.2, the implicit dependency on material-icons-core was removed. If your project uses Icons.Default.* or any Material icon, add it explicitly.

gradle/libs.versions.toml

[versions]
kotlin               = "2.1.21"
agp                  = "8.10.0"
composeMultiplatform = "1.8.2"   # org.jetbrains.compose plugin version
coroutines           = "1.10.2"
lifecycle            = "2.9.0"

[libraries]
# ✅ Correct module for commonMain
# The CMP plugin maps this → androidx.compose.material3 on Android automatically
compose-material3          = { module = "org.jetbrains.compose.material3:material3",            version.ref = "composeMultiplatform" }
compose-runtime            = { module = "org.jetbrains.compose.runtime:runtime",                version.ref = "composeMultiplatform" }
compose-foundation         = { module = "org.jetbrains.compose.foundation:foundation",          version.ref = "composeMultiplatform" }
compose-ui                 = { module = "org.jetbrains.compose.ui:ui",                          version.ref = "composeMultiplatform" }
# Declare explicitly — no longer a transitive dep since CMP 1.8.2
compose-material-icons-core = { module = "org.jetbrains.compose.material:material-icons-core", version.ref = "composeMultiplatform" }
compose-ui-tooling-preview  = { module = "org.jetbrains.compose.ui:ui-tooling-preview",        version.ref = "composeMultiplatform" }

[plugins]
kotlinMultiplatform  = { id = "org.jetbrains.kotlin.multiplatform",       version.ref = "kotlin" }
androidApplication   = { id = "com.android.application",                  version.ref = "agp" }
composeMultiplatform = { id = "org.jetbrains.compose",                    version.ref = "composeMultiplatform" }
composeCompiler      = { id = "org.jetbrains.kotlin.plugin.compose",      version.ref = "kotlin" }

composeApp/build.gradle.kts

kotlin {
    sourceSets {
        commonMain.dependencies {
            // ✅ Use libs.* — NOT the deprecated compose.* plugin accessors
            implementation(libs.compose.runtime)
            implementation(libs.compose.foundation)
            implementation(libs.compose.ui)
            implementation(libs.compose.material3)
            implementation(libs.compose.material.icons.core)  // explicit since CMP 1.8.2
        }
        androidMain.dependencies {
            implementation(libs.compose.ui.tooling.preview)
        }
    }
}

Module mapping (how it works)

Source set	Module in toml	What Gradle actually resolves
commonMain	org.jetbrains.compose.material3:material3	JetBrains multiplatform artifact
androidMain (via CMP plugin metadata)	same toml entry	androidx.compose.material3:material3
jvmMain (Desktop)	same toml entry	JetBrains desktop artifact

You never need to manually switch to androidx.compose.material3 in build files — the CMP Gradle plugin metadata handles the platform mapping transparently.

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Official Docs

• Material 3
• Compose Material 3
• M3 Theme Builder
• Compose Multiplatform
• Material3 Adaptive
• CMP Release Notes