name: design-tokens
description: "Apply design token patterns using Tailwind CSS 4 @theme directive: CSS variables, semantic naming, color systems, typography scales, spacing, dark mode. Use when designing UI systems, reviewing design consistency, or establishing brand guidelines. Integrates with frontend-design skill for aesthetic execution."

Design Tokens

Design tokens are the single source of truth for design decisions.

Philosophy

• CSS-first: Define tokens in CSS @theme, not JavaScript config
• Semantic naming: --color-primary not --color-blue-500
• Brand-tinted neutrals: Add imperceptible brand hue (chroma 0.005-0.02), not pure gray
• OKLCH colors: Perceptually uniform, better than RGB/HSL

Why Tailwind CSS 4 @theme

• CSS-native (no build step overhead)
• Type-safe auto-completion
• CSS variable integration (var(--color-primary))
• Dark mode built-in

Migration from Tailwind 3: Delete tailwind.config.js, move to CSS @theme.

Basic @theme Structure

@import "tailwindcss";

@theme {
  /* Brand hue - single source of truth */
  --brand-hue: 250;

  /* Colors - OKLCH with semantic names */
  --color-primary: oklch(0.6 0.2 var(--brand-hue));
  --color-background: oklch(0.995 0.005 var(--brand-hue));  /* Brand-tinted */
  --color-foreground: oklch(0.15 0.02 var(--brand-hue));

  /* Typography */
  --font-sans: "Inter Variable", system-ui, sans-serif;
  --font-size-base: 1rem;

  /* Spacing (8-point grid) */
  --spacing-md: 1rem;
  --radius-md: 0.5rem;
}

Best Practices

Do

• Use semantic names (--color-primary)
• Use OKLCH colors
• Tint neutrals with brand hue
• Follow 8-point spacing grid
• Support dark mode from start
• Create component tokens

Don't

• Hardcode values
• Use pure grays (chroma 0)
• Use generic fonts (Inter/Roboto)
• Skip dark mode
• Create too many tokens initially

Dark Mode Pattern

Same brand hue, inverted lightness:

@theme {
  --brand-hue: 250;
  --color-background: oklch(0.995 0.005 var(--brand-hue));

  @media (prefers-color-scheme: dark) {
    --color-background: oklch(0.12 0.015 var(--brand-hue));
  }
}

References

Detailed patterns:
- references/color-system.md — OKLCH, semantic colors, brand-tinted neutrals
- references/typography.md — Type scale, font pairings, font loading
- references/spacing.md — 8-point grid, radius, shadows, breakpoints, z-index
- references/dark-mode.md — System preference, manual toggle, component
- references/component-tokens.md — Button, input, card, animation, WebGL

Integration

Design tokens provide the foundation; frontend-design provides aesthetic direction.

1. Load design-tokens for the system
2. Load frontend-design for aesthetic execution
3. Result: Consistent system + distinctive design

"Design tokens are contracts between design and development."