Design System Starter

Quick Reference

Bundled Resources

• references/component-examples.md - Complete component implementations
• templates/design-tokens-template.json - W3C design token format
• templates/component-template.tsx - React component template
• checklists/design-system-checklist.md - Design system audit checklist

Design System Philosophy

What is a Design System?

A design system is more than a component library—it's a collection of:

1. Design Tokens: Foundational design decisions (colors, spacing, typography)
2. Components: Reusable UI building blocks
3. Patterns: Common UX solutions and compositions
4. Guidelines: Rules, principles, and best practices
5. Documentation: How to use everything effectively

Core Principles

1. Consistency Over Creativity

• Predictable patterns reduce cognitive load
• Users learn once, apply everywhere
• Designers and developers speak the same language

2. Accessible by Default

• WCAG 2.1 Level AA compliance minimum
• Keyboard navigation built-in
• Screen reader support from the start

3. Scalable and Maintainable

• Design tokens enable global changes
• Component composition reduces duplication
• Versioning and deprecation strategies

4. Developer-Friendly

• Clear API contracts
• Comprehensive documentation
• Easy to integrate and customize

Design Tokens

Design tokens are the atomic design decisions that define your system's visual language.

Token Categories

1. Color Tokens

Primitive Colors (Raw values):

{
  "color": {
    "primitive": {
      "blue": {
        "50": "#eff6ff",
        "100": "#dbeafe",
        "200": "#bfdbfe",
        "300": "#93c5fd",
        "400": "#60a5fa",
        "500": "#3b82f6",
        "600": "#2563eb",
        "700": "#1d4ed8",
        "800": "#1e40af",
        "900": "#1e3a8a",
        "950": "#172554"
      }
    }
  }
}

Semantic Colors (Contextual meaning):

{
  "color": {
    "semantic": {
      "brand": {
        "primary": "{color.primitive.blue.600}",
        "primary-hover": "{color.primitive.blue.700}",
        "primary-active": "{color.primitive.blue.800}"
      },
      "text": {
        "primary": "{color.primitive.gray.900}",
        "secondary": "{color.primitive.gray.600}",
        "tertiary": "{color.primitive.gray.500}",
        "disabled": "{color.primitive.gray.400}",
        "inverse": "{color.primitive.white}"
      },
      "background": {
        "primary": "{color.primitive.white}",
        "secondary": "{color.primitive.gray.50}",
        "tertiary": "{color.primitive.gray.100}"
      },
      "feedback": {
        "success": "{color.primitive.green.600}",
        "warning": "{color.primitive.yellow.600}",
        "error": "{color.primitive.red.600}",
        "info": "{color.primitive.blue.600}"
      }
    }
  }
}

Accessibility: Ensure color contrast ratios meet WCAG 2.1 Level AA:

• Normal text: 4.5:1 minimum
• Large text (18pt+ or 14pt+ bold): 3:1 minimum
• UI components and graphics: 3:1 minimum

2. Typography Tokens

{
  "typography": {
    "fontFamily": {
      "sans": "'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif",
      "serif": "'Georgia', 'Times New Roman', serif",
      "mono": "'Fira Code', 'Courier New', monospace"
    },
    "fontSize": {
      "xs": "0.75rem",     // 12px
      "sm": "0.875rem",    // 14px
      "base": "1rem",      // 16px
      "lg": "1.125rem",    // 18px
      "xl": "1.25rem",     // 20px
      "2xl": "1.5rem",     // 24px
      "3xl": "1.875rem",   // 30px
      "4xl": "2.25rem",    // 36px
      "5xl": "3rem"        // 48px
    },
    "fontWeight": {
      "normal": 400,
      "medium": 500,
      "semibold": 600,
      "bold": 700
    },
    "lineHeight": {
      "tight": 1.25,
      "normal": 1.5,
      "relaxed": 1.75,
      "loose": 2
    },
    "letterSpacing": {
      "tight": "-0.025em",
      "normal": "0",
      "wide": "0.025em"
    }
  }
}

3. Spacing Tokens

Scale: Use a consistent spacing scale (commonly 4px or 8px base)

{
  "spacing": {
    "0": "0",
    "1": "0.25rem",   // 4px
    "2": "0.5rem",    // 8px
    "3": "0.75rem",   // 12px
    "4": "1rem",      // 16px
    "5": "1.25rem",   // 20px
    "6": "1.5rem",    // 24px
    "8": "2rem",      // 32px
    "10": "2.5rem",   // 40px
    "12": "3rem",     // 48px
    "16": "4rem",     // 64px
    "20": "5rem",     // 80px
    "24": "6rem"      // 96px
  }
}

Component-Specific Spacing:

{
  "component": {
    "button": {
      "padding-x": "{spacing.4}",
      "padding-y": "{spacing.2}",
      "gap": "{spacing.2}"
    },
    "card": {
      "padding": "{spacing.6}",
      "gap": "{spacing.4}"
    }
  }
}

4. Border Radius Tokens

{
  "borderRadius": {
    "none": "0",
    "sm": "0.125rem",   // 2px
    "base": "0.25rem",  // 4px
    "md": "0.375rem",   // 6px
    "lg": "0.5rem",     // 8px
    "xl": "0.75rem",    // 12px
    "2xl": "1rem",      // 16px
    "full": "9999px"
  }
}

5. Shadow Tokens

{
  "shadow": {
    "xs": "0 1px 2px 0 rgba(0, 0, 0, 0.05)",
    "sm": "0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px -1px rgba(0, 0, 0, 0.1)",
    "base": "0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1)",
    "md": "0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1)",
    "lg": "0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.1)",
    "xl": "0 25px 50px -12px rgba(0, 0, 0, 0.25)"
  }
}

Component Architecture

Atomic Design Methodology

Atoms → Molecules → Organisms → Templates → Pages

Atoms (Primitive Components)

Basic building blocks that can't be broken down further.

Examples:

• Button
• Input
• Label
• Icon
• Badge
• Avatar

Button Component:

interface ButtonProps {
  variant?: 'primary' | 'secondary' | 'outline' | 'ghost';
  size?: 'sm' | 'md' | 'lg';
  disabled?: boolean;
  loading?: boolean;
  icon?: React.ReactNode;
  children: React.ReactNode;
}

See references/component-examples.md for complete Button implementation with variants, sizes, and styling patterns.

Molecules (Simple Compositions)

Groups of atoms that function together.

Examples:

• SearchBar (Input + Button)
• FormField (Label + Input + ErrorMessage)
• Card (Container + Title + Content + Actions)

FormField Molecule:

interface FormFieldProps {
  label: string;
  name: string;
  error?: string;
  hint?: string;
  required?: boolean;
  children: React.ReactNode;
}

See references/component-examples.md for FormField, Card (compound component pattern), Input with variants, Modal, and more composition examples.

Organisms (Complex Compositions)

Complex UI components made of molecules and atoms.

Examples:

• Navigation Bar
• Product Card Grid
• User Profile Section
• Modal Dialog

Templates (Page Layouts)

Page-level structures that define content placement.

Examples:

• Dashboard Layout (Sidebar + Header + Main Content)
• Marketing Page Layout (Hero + Features + Footer)
• Settings Page Layout (Tabs + Content Panels)

Pages (Specific Instances)

Actual pages with real content.

Component API Design

Props Best Practices

1. Predictable Prop Names

// ✅ Good: Consistent naming
<Button variant="primary" size="md" />
<Input variant="outlined" size="md" />

// ❌ Bad: Inconsistent
<Button type="primary" sizeMode="md" />
<Input style="outlined" inputSize="md" />

2. Sensible Defaults

// ✅ Good: Provides defaults
interface ButtonProps {
  variant?: 'primary' | 'secondary';  // Default: primary
  size?: 'sm' | 'md' | 'lg';          // Default: md
}

// ❌ Bad: Everything required
interface ButtonProps {
  variant: 'primary' | 'secondary';
  size: 'sm' | 'md' | 'lg';
  color: string;
  padding: string;
}

3. Composition Over Configuration

// ✅ Good: Composable
<Card>
  <Card.Header>
    <Card.Title>Title</Card.Title>
  </Card.Header>
  <Card.Body>Content</Card.Body>
  <Card.Footer>Actions</Card.Footer>
</Card>

// ❌ Bad: Too many props
<Card
  title="Title"
  content="Content"
  footerContent="Actions"
  hasHeader={true}
  hasFooter={true}
/>

4. Polymorphic Components Allow components to render as different HTML elements:

<Button as="a" href="/login">Login</Button>
<Button as="button" onClick={handleClick}>Click Me</Button>

See references/component-examples.md for complete polymorphic component TypeScript patterns.

Theming and Dark Mode

Theme Structure

interface Theme {
  colors: {
    brand: {
      primary: string;
      secondary: string;
    };
    text: {
      primary: string;
      secondary: string;
    };
    background: {
      primary: string;
      secondary: string;
    };
    feedback: {
      success: string;
      warning: string;
      error: string;
      info: string;
    };
  };
  typography: {
    fontFamily: {
      sans: string;
      mono: string;
    };
    fontSize: Record<string, string>;
  };
  spacing: Record<string, string>;
  borderRadius: Record<string, string>;
  shadow: Record<string, string>;
}

Dark Mode Implementation

Approach 1: CSS Variables

:root {
  --color-bg-primary: #ffffff;
  --color-text-primary: #000000;
}

[data-theme="dark"] {
  --color-bg-primary: #1a1a1a;
  --color-text-primary: #ffffff;
}

Approach 2: Tailwind CSS Dark Mode

<div className="bg-white dark:bg-gray-900 text-gray-900 dark:text-white">
  Content
</div>

Approach 3: Styled Components ThemeProvider

const lightTheme = { background: '#fff', text: '#000' };
const darkTheme = { background: '#000', text: '#fff' };

<ThemeProvider theme={isDark ? darkTheme : lightTheme}>
  <App />
</ThemeProvider>

Accessibility Guidelines

WCAG 2.1 Level AA Compliance

Color Contrast

• Normal text (< 18pt): 4.5:1 minimum
• Large text (≥ 18pt or ≥ 14pt bold): 3:1 minimum
• UI components: 3:1 minimum

Tools: Use contrast checkers like WebAIM Contrast Checker

Keyboard Navigation

// ✅ All interactive elements must be keyboard accessible
<button
  onClick={handleClick}
  onKeyDown={(e) => e.key === 'Enter' && handleClick()}
>
  Click me
</button>

// ✅ Focus management
<Modal>
  <FocusTrap>
    {/* Modal content */}
  </FocusTrap>
</Modal>

ARIA Attributes

Essential ARIA patterns:

• aria-label: Provide accessible names
• aria-expanded: Communicate expanded/collapsed state
• aria-controls: Associate controls with content
• aria-live: Announce dynamic content changes

Screen Reader Support

• Use semantic HTML elements (<button>, <nav>, <main>)
• Avoid div/span soup for interactive elements
• Provide meaningful labels for all controls

See references/component-examples.md for complete accessibility examples including Skip Links, focus traps, and ARIA patterns.

Documentation Standards

Component Documentation Template

Each component should document:

• Purpose: What the component does
• Usage: Import statement and basic example
• Variants: Available visual styles
• Props: Complete prop table with types, defaults, descriptions
• Accessibility: Keyboard support, ARIA attributes, screen reader behavior
• Examples: Common use cases with code

Use Storybook, Docusaurus, or similar tools for interactive documentation.

See templates/component-template.tsx for the standard component structure.

Design System Workflow

1. Design Phase

• Audit existing patterns: Identify inconsistencies
• Define design tokens: Colors, typography, spacing
• Create component inventory: List all needed components
• Design in Figma: Create component library

2. Development Phase

• Set up tooling: Storybook, TypeScript, testing
• Implement tokens: CSS variables or theme config
• Build atoms first: Start with primitives
• Compose upward: Build molecules, organisms
• Document as you go: Write docs alongside code

3. Adoption Phase

• Create migration guide: Help teams adopt
• Provide codemods: Automate migrations when possible
• Run workshops: Train teams on usage
• Gather feedback: Iterate based on real usage

4. Maintenance Phase

• Version semantically: Major/minor/patch releases
• Deprecation strategy: Phase out old components gracefully
• Changelog: Document all changes
• Monitor adoption: Track usage across products

Quick Start Checklist

When creating a new design system:

• Define design principles and values
• Establish design token structure (colors, typography, spacing)
• Create primitive color palette (50-950 scale)
• Define semantic color tokens (brand, text, background, feedback)
• Set typography scale and font families
• Establish spacing scale (4px or 8px base)
• Design atomic components (Button, Input, Label, etc.)
• Implement theming system (light/dark mode)
• Ensure WCAG 2.1 Level AA compliance
• Set up documentation (Storybook or similar)
• Create usage examples for each component
• Establish versioning and release strategy
• Create migration guides for adopting teams

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