/extract-design-md

React / Next.js / Tailwind Extraction Patterns

This reference covers the most common frontend stack: React components with Tailwind CSS (and optionally CSS Modules, styled-components, or Emotion).

File Discovery Order

Read these files in priority order — higher-priority files give you the intended design system, lower-priority files show what actually shipped:

1. tailwind.config.js / tailwind.config.ts — The single most important file. Custom theme.extend.colors, fontFamily, spacing, borderRadius, and screens are the design system definition.

2. globals.css / global.css / index.css — CSS custom properties (--*), @layer directives, @font-face declarations, and base styles.

3. theme.ts / theme.js / tokens.ts — Explicit design token files. May export objects consumed by Tailwind config or CSS-in-JS providers.

4. src/app/layout.tsx or src/App.tsx — Root layout. Shows the global font setup (via next/font or <link>), body background, and overall structure.

5. Component files (*.tsx / *.jsx) — Look at 5-8 representative components to understand usage patterns.

Tailwind Config Extraction

The Tailwind config is structured and machine-readable. Extract directly:

// tailwind.config.js
module.exports = {
  theme: {
    extend: {
      colors: {
        primary: '#294056',      // → "Deep Muted Teal-Navy" — Primary CTA
        background: '#FCFAFA',   // → "Warm Barely-There Cream" — Page BG
      },
      fontFamily: {
        sans: ['Manrope', 'sans-serif'],
      },
      borderRadius: {
        card: '12px',
        button: '8px',
      },
      spacing: {
        section: '5rem',
      }
    }
  }
}

Map each custom value to a descriptive name and role.

CSS Custom Properties

Look for :root or html blocks in global CSS:

:root {
  --color-primary: #294056;
  --color-bg: #FCFAFA;
  --font-heading: 'Manrope', sans-serif;
  --radius-card: 12px;
  --spacing-section: 5rem;
}

These are explicitly declared tokens — use their names as clues for their intended role.

Next.js Font Patterns

Next.js uses next/font for optimized font loading:

import { Inter, Playfair_Display } from 'next/font/google'

const inter = Inter({ subsets: ['latin'], variable: '--font-inter' })
const playfair = Playfair_Display({ subsets: ['latin'], variable: '--font-display' })

The variable names hint at usage: --font-display for headlines, --font-inter for body.

Component Scanning Strategy

Don't read every component. Focus on these archetypes:

For each, look at the className prop for Tailwind classes or the styled() / css() calls for CSS-in-JS values.

CSS-in-JS Patterns (styled-components / Emotion)

If the project uses CSS-in-JS, look for theme providers:

// ThemeProvider wrapping the app
const theme = {
  colors: {
    primary: '#294056',
    background: '#FCFAFA',
  },
  fonts: {
    heading: 'Manrope, sans-serif',
  },
  radii: {
    card: '12px',
    button: '8px',
  }
}

This theme object is the design system. Extract directly.

Component Library Integration

If the project uses Chakra UI, Material UI, Ant Design, or shadcn/ui:

• Chakra: Look for extendTheme() calls — these override defaults.
• MUI: Look for createTheme() — palette, typography, and spacing overrides.
• Ant Design: Look for ConfigProvider theme prop or theme.ts overrides.
• shadcn/ui: Colors are defined as CSS custom properties in globals.css. Check components.json for the style configuration.

The overrides are the design system — default values are the library's generic styling and should be noted but not emphasized.

Responsive Patterns

Check Tailwind's screens config and look for responsive class prefixes (sm:, md:, lg:, xl:) in components:

screens: {
  sm: '640px',   // Mobile landscape
  md: '768px',   // Tablet
  lg: '1024px',  // Desktop
  xl: '1280px',  // Large desktop
  '2xl': '1536px'
}

Look for container configuration and max-width patterns on layout components to determine content width strategy.