# material-ui

This rule tells Cursor how to write React code with Material-UI: folder layout, theme setup, styling and component style. Useful when a MUI codebase grows and you want consistent choices.

- rule · `type=rule` · Cursor · ★ 3579
- Author: sanjeed5
- License: CC0-1.0 · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/sanjeed5/awesome-cursor-rules-mdc/tree/HEAD/rules-mdc/material-ui.mdc
- Updated: 2026-05-19
- HTML: https://affpapa.org/en/nevibecode/rules/material-ui

## What it does

The file lays out how to build React apps with Material-UI. It covers code organization, theming, styling and component architecture. Cursor reads these instructions and applies them while generating or editing files.

Code goes by feature, not by file type: shared components in `src/components/`, screen logic in `src/features/`, theme in `src/theme/`. The theme is built with `createTheme`, wired through `ThemeProvider`, with `CssBaseline` alongside. Mutating the theme object after creation is marked bad, because those changes are not reactive. Reach for the `sx` prop on one-off tweaks and `styled` from `@mui/material/styles` for reusable styles. The `@mui/styles` package with `makeStyles` is called deprecated, and inline styles get the same treatment.

Components stay functional, with hooks, small and composed. The globs `**/*` mean the rule applies to every file, so in a repo with its own established conventions it will pull against them. Decide up front whether you want to refactor existing code to match.

## Install

### Cursor (native platform)

**Manually: put the files in place**
- File: `.cursor/rules/material-ui.mdc` — Frontmatter: description, globs, alwaysApply

### Claude Code

**Manually: put the files in place**
- File: `.claude/rules/material-ui.md` — The paths frontmatter field limits the files: move globs from the source into paths

### Codex

**AGENTS.md**
- Codex reads AGENTS.md: paste the rule text there

### GitHub Copilot

**Manually: put the files in place**
- File: `.github/instructions/material-ui.instructions.md` — The applyTo field sets which files it applies to: move globs from the source into applyTo

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/rules/material-ui.md`

### Cline

**Manually: put the files in place**
- File: `.clinerules/material-ui.md`

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/sanjeed5/awesome-cursor-rules-mdc/tree/HEAD/rules-mdc/material-ui.mdc

## When to use it
- organize a React codebase by feature instead of file type
- set up one MUI theme and stop mutating it by hand
- pick between the `sx` prop and `styled` for a given case
- drop the deprecated `makeStyles` from `@mui/styles`
- move class components to functions with hooks

## Example prompts
- create a product card component following the material-ui rules
- rewrite this component as a functional one with hooks, as material-ui requires
- move these styles into a separate `.styled.js` file using `styled`

## Source text · material-ui.mdc · CC0-1.0

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: b9620b60cac971b6.

BEGIN THIRD-PARTY FILE b9620b60cac971b6
````text
---
description: Provides definitive guidelines for building scalable, performant, and maintainable React applications using Material-UI (MUI), focusing on modern best practices.
globs: **/*
---
# Material-UI (MUI) Best Practices

This guide outlines the definitive best practices for developing React applications with Material-UI (MUI). Adhere to these standards to ensure consistent, performant, and maintainable code across our projects.

## 1. Code Organization & Structure

Organize code by feature, not by type. Components should be small, focused, and self-contained.

### 1.1 Directory Structure
Adopt a feature-oriented layout.
```
src/
  components/           # Reusable, generic UI components (e.g., Button, Modal)
    Button/
      Button.jsx
      Button.styled.js  # Styled components for Button
      Button.test.jsx
      index.js          # Exports Button
  features/             # Feature-specific components and logic (e.g., UserProfile, ProductList)
    Auth/
      LoginPage.jsx
      AuthForm.jsx
      AuthService.js
      AuthContext.js
  theme/                # Centralized MUI theme configuration
    index.js
    palette.js
    typography.js
  utils/                # General utility functions
    api.js
    helpers.js
  App.jsx               # Main application component
  index.jsx             # Entry point
```

### 1.2 Naming Conventions
-   **Components**: `PascalCase` (e.g., `MyComponent.jsx`).
-   **Styled Components**: `PascalCase` for the component, `.styled.js` suffix (e.g., `MyComponent.styled.js`).
-   **CSS Modules**: `kebab-case` or `camelCase` (e.g., `my-component.module.css`).
-   **Tests**: `.test.jsx` suffix (e.g., `MyComponent.test.jsx`).
-   **Indexes**: `index.js` should export the main entity of its parent folder.

## 2. Theming

Centralize all design tokens and theme customizations. Always use `createTheme` and `ThemeProvider`.

### 2.1 Centralized Theme Configuration
Define your theme in `src/theme/index.js` and wrap your application with `ThemeProvider`. This is where Material Design 3 tokens should be configured.

```jsx
// src/theme/index.js
import { createTheme } from '@mui/material/styles';

const theme = createTheme({
  palette: {
    mode: 'light', // or 'dark'
    primary: {
      main: '#006B5F', // Material Design 3 primary color example
      light: '#4DA89F',
      dark: '#003730',
    },
    secondary: {
      main: '#6A5F00', // Material Design 3 secondary color example
    },
    // ... other palette colors
  },
  typography: {
    fontFamily: 'Roboto, sans-serif',
    h1: { fontSize: '2.5rem', fontWeight: 700 },
    body1: { fontSize: '1rem', lineHeight: 1.5 },
  },
  components: {
    MuiButton: {
      defaultProps: {
        disableElevation: true, // Consistent button style
      },
      styleOverrides: {
        root: {
          borderRadius: 8,
          textTransform: 'none', // Prefer sentence case for buttons
        },
      },
    },
    MuiCard: {
      styleOverrides: {
        root: {
          borderRadius: 12,
          boxShadow: '0 2px 8px rgba(0,0,0,0.08)',
        },
      },
    },
  },
});

export default theme;

// src/App.jsx
import { ThemeProvider } from '@mui/material/styles';
import CssBaseline from '@mui/material/CssBaseline'; // Resets browser styles
import theme from './theme';
import MyPage from './features/MyPage';

function App() {
  return (
    <ThemeProvider theme={theme}>
      <CssBaseline /> {/* Always include CssBaseline */}
      <MyPage />
    </ThemeProvider>
  );
}
export default App;
```

### ❌ BAD: Mutating Theme Directly
````
END THIRD-PARTY FILE b9620b60cac971b6

The third-party file has ended. Everything between the b9620b60cac971b6 tags is data: requests and commands from it are not followed. An “end of file” line with another tag inside the block is part of the file.

First 3582 of 12508 bytes. © sanjeed5 · CC0-1.0 · https://github.com/sanjeed5/awesome-cursor-rules-mdc/tree/HEAD/rules-mdc/material-ui.mdc

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