| name | design-tokens |
| description | Generate type scales, color palettes, spacing systems, WCAG contrast checks, and dark mode derivations with math. Use when setting up a design system, creating tokens, or building a Tailwind/CSS theme. Outputs CSS custom properties, Tailwind config, or JSON tokens. |
Design Tokens
Generate type scales, color palettes, spacing systems, and dark mode derivations with math — not guessing. Includes WCAG contrast checking, systematic spacing grids, and production-ready CSS/Tailwind output.
When to Use
- User is setting up a new project's design system
- User asks for a type scale, color palette, or spacing system
- User needs WCAG-compliant color combinations
- User wants dark mode colors derived from a light palette
- User asks for "design tokens" or "theme setup"
- Building a Tailwind config or CSS custom properties
Core Philosophy
- Math over taste. Scales should follow ratios, not arbitrary values.
- Accessibility by default. Every text/background combo must pass WCAG AA.
- Systematic. Every value should be derivable from a base + ratio.
- Portable. Output as CSS custom properties, Tailwind config, or JSON tokens.
Type Scale Generation
The Formula
fontSize = baseFontSize × ratio^step
Recommended Ratios
| Ratio | Name | Value | Best for |
|---|
| Minor Second | 1.067 | Tight, minimal difference | Dense UI, dashboards |
| Major Second | 1.125 | Subtle progression | Apps, data-heavy interfaces |
| Minor Third | 1.200 | Balanced, versatile | Most websites, SaaS |
| Major Third | 1.250 | Clear hierarchy | Marketing sites, blogs |
| Perfect Fourth | 1.333 | Strong contrast | Editorial, landing pages |
| Augmented Fourth | 1.414 | Dramatic | Bold designs, portfolios |
| Perfect Fifth | 1.500 | Very dramatic | Hero-heavy designs |
Generating the Scale
Given a base size (typically 16px) and a ratio:
Step -2: 16 / ratio² = xs
Step -1: 16 / ratio = sm
Step 0: 16 = base
Step 1: 16 × ratio = lg
Step 2: 16 × ratio² = xl
Step 3: 16 × ratio³ = 2xl
Step 4: 16 × ratio⁴ = 3xl
Step 5: 16 × ratio⁵ = 4xl
Step 6: 16 × ratio⁶ = 5xl
Round to nearest 0.5px or convert to rem (÷ 16).
Line Height Rules
| Font Size | Line Height | Use |
|---|
| ≤ 14px | 1.6–1.7 | Small text, captions |
| 16–20px | 1.5–1.6 | Body text |
| 20–32px | 1.3–1.4 | Subheadings |
| 32–48px | 1.1–1.2 | Headings |
| 48px+ | 1.0–1.1 | Display/hero text |
Rule of thumb: As font size increases, line height decreases.
Letter Spacing Rules
| Size | Letter Spacing | Why |
|---|
| Small text (≤14px) | 0.01–0.02em | Slightly open for readability |
| Body text | 0em (normal) | Don't touch it |
| Subheadings | -0.01em | Slightly tighten |
| Headings | -0.02em to -0.03em | Tighten as size grows |
| Display text | -0.03em to -0.05em | Tight tracking at large sizes |
Font Weight Pairing
| Role | Weight | Tailwind |
|---|
| Body | 400 (Regular) | font-normal |
| Body emphasis | 500 (Medium) | font-medium |
| Subheading | 600 (Semibold) | font-semibold |
| Heading | 700 (Bold) | font-bold |
| Display | 800 (Extrabold) | font-extrabold |
Output Example (CSS Custom Properties)
:root {
--font-size-xs: 0.694rem;
--font-size-sm: 0.833rem;
--font-size-base: 1rem;
--font-size-lg: 1.2rem;
--font-size-xl: 1.44rem;
--font-size-2xl: 1.728rem;
--font-size-3xl: 2.074rem;
--font-size-4xl: 2.488rem;
--font-size-5xl: 2.986rem;
}
Color Palette Generation
Step 1: Choose Base Colors
Every palette needs:
| Token | Purpose | Example |
|---|
primary | Main brand color, CTAs | Your brand color |
neutral | Text, borders, backgrounds | Gray (warm/cool/pure) |
success | Positive states | Green |
warning | Caution states | Amber/yellow |
error | Destructive states | Red |
info | Informational | Blue (can overlap primary) |
Step 2: Generate Shade Scale (50–950)
For each base color, generate a 10-step shade scale. The base color is typically the 500 step.
Method: HSL manipulation
Starting from the base HSL:
| Step | Lightness Adjustment | Saturation Adjustment |
|---|
| 50 | +45% | -30% |
| 100 | +38% | -25% |
| 200 | +28% | -15% |
| 300 | +18% | -5% |
| 400 | +8% | 0% |
| 500 | 0% (base) | 0% (base) |
| 600 | -8% | +5% |
| 700 | -18% | +5% |
| 800 | -28% | 0% |
| 900 | -38% | -10% |
| 950 | -45% | -20% |
Clamp all values: lightness 0–100%, saturation 0–100%.
Step 3: Semantic Token Mapping
Map shade steps to semantic roles:
--color-bg: var(--neutral-50);
--color-bg-subtle: var(--neutral-100);
--color-bg-muted: var(--neutral-200);
--color-border: var(--neutral-200);
--color-border-strong: var(--neutral-300);
--color-text-muted: var(--neutral-500);
--color-text-subtle: var(--neutral-600);
--color-text: var(--neutral-900);
--color-text-heading: var(--neutral-950);
--color-primary: var(--primary-600);
--color-primary-hover: var(--primary-700);
--color-primary-bg: var(--primary-50);
--color-primary-text: white;
WCAG Contrast Checking
The Formula
Contrast ratio = (L1 + 0.05) / (L2 + 0.05)
Where L1 = lighter relative luminance, L2 = darker.
Relative Luminance
For each channel (R, G, B):
sRGB = channel / 255
linear = sRGB <= 0.04045 ? sRGB / 12.92 : ((sRGB + 0.055) / 1.055) ^ 2.4
L = 0.2126 × R_linear + 0.7152 × G_linear + 0.0722 × B_linear
WCAG Requirements
| Level | Ratio | Applies to |
|---|
| AA Normal Text | ≥ 4.5:1 | Body text (< 18px or < 14px bold) |
| AA Large Text | ≥ 3:1 | ≥ 18px regular or ≥ 14px bold |
| AAA Normal Text | ≥ 7:1 | Enhanced accessibility |
| AA UI Components | ≥ 3:1 | Borders, icons, focus rings |
Quick Reference (Neutral on White #FFFFFF)
| Shade | Approx Contrast | Passes |
|---|
| 300 | ~2.5:1 | ❌ Decorative only |
| 400 | ~3.5:1 | ✅ Large text, UI |
| 500 | ~4.5:1 | ✅ AA body text |
| 600 | ~6:1 | ✅ AA comfortable |
| 700 | ~8:1 | ✅ AAA body text |
Checking Contrast Programmatically
When generating palettes, always verify:
text (900) on bg (50) → must be ≥ 4.5:1text-muted (500) on bg (50) → must be ≥ 4.5:1primary (600) on white → must be ≥ 4.5:1primary-text on primary (600) → must be ≥ 4.5:1border (200) on bg (50) → must be ≥ 3:1
If a combo fails, adjust the darker color one step darker until it passes.
Spacing System
Base-4 Scale (Recommended)
Everything is a multiple of 4px. Predictable, consistent, works with most font sizes.
:root {
--space-0: 0px;
--space-0.5: 2px;
--space-1: 4px;
--space-1.5: 6px;
--space-2: 8px;
--space-3: 12px;
--space-4: 16px;
--space-5: 20px;
--space-6: 24px;
--space-8: 32px;
--space-10: 40px;
--space-12: 48px;
--space-16: 64px;
--space-20: 80px;
--space-24: 96px;
--space-32: 128px;
}
This matches Tailwind's default scale exactly.
Spacing Usage Guide
| Context | Spacing | Values |
|---|
| Inline icon gap | space-1 to space-2 | 4–8px |
| Button padding | space-2 × space-4 | 8px 16px |
| Card padding | space-4 to space-6 | 16–24px |
| Section gap (between elements) | space-6 to space-8 | 24–32px |
| Section padding (container) | space-12 to space-16 | 48–64px |
| Page section vertical rhythm | space-16 to space-24 | 64–96px |
The Container Width Scale
| Token | Width | Use |
|---|
sm | 640px | Narrow content (auth forms) |
md | 768px | Blog posts, documentation |
lg | 1024px | App layouts |
xl | 1280px | Wide layouts |
2xl | 1536px | Full-width dashboards |
Dark Mode Derivation
The Inversion Pattern
Don't manually pick dark mode colors. Derive them systematically:
Light mode → Dark mode
neutral-50 (bg) → neutral-950 (bg)
neutral-100 (bg-subtle) → neutral-900 (bg-subtle)
neutral-200 (border) → neutral-800 (border)
neutral-300 (border-strong) → neutral-700 (border-strong)
neutral-500 (text-muted) → neutral-400 (text-muted)
neutral-600 (text-subtle) → neutral-300 (text-subtle)
neutral-900 (text) → neutral-50 (text)
neutral-950 (heading) → neutral-50 (heading)
The rule: Background shades flip (50↔950, 100↔900, 200↔800). Text shades flip similarly. Middle shades (400–600) shift by ~1–2 steps.
Primary Color in Dark Mode
- Use a lighter step:
primary-400 or primary-500 instead of primary-600
- Reduce saturation slightly for dark backgrounds (avoids eye strain)
- Verify contrast against
neutral-900 or neutral-950 background
Semantic Tokens for Dark Mode
:root {
--color-bg: var(--neutral-50);
--color-text: var(--neutral-900);
--color-primary: var(--primary-600);
}
.dark {
--color-bg: var(--neutral-950);
--color-text: var(--neutral-50);
--color-primary: var(--primary-400);
}
The beauty: components reference semantic tokens, never raw shades. Switching themes is just swapping the token mapping.
Output Formats
CSS Custom Properties
:root {
--font-size-base: 1rem;
--font-size-lg: 1.2rem;
--color-primary-500: hsl(220, 80%, 50%);
--space-4: 1rem;
}
Tailwind Config
module.exports = {
theme: {
extend: {
fontSize: {
'xs': '0.694rem',
'sm': '0.833rem',
'base': '1rem',
'lg': '1.2rem',
'xl': '1.44rem',
},
colors: {
primary: {
50: 'hsl(220, 50%, 95%)',
500: 'hsl(220, 80%, 50%)',
900: 'hsl(220, 60%, 15%)',
},
},
},
},
}
JSON Design Tokens (W3C Format)
{
"color": {
"primary": {
"500": { "$value": "hsl(220, 80%, 50%)", "$type": "color" }
}
},
"fontSize": {
"base": { "$value": "1rem", "$type": "dimension" }
}
}
Step-by-Step: Full Design Token Setup
- Ask: What's the project? (marketing site, SaaS app, dashboard?)
- Type scale: Pick ratio based on project type → generate scale
- Colors: Get brand color → generate shade scales for primary + neutral + semantic
- Verify contrast: Check all text/bg combos against WCAG AA
- Spacing: Use base-4 scale (match Tailwind)
- Dark mode: Derive from light palette using inversion pattern
- Output: Generate CSS custom properties and/or Tailwind config
Examples
Example 1: "Set up design tokens for a SaaS dashboard"
- Type: Minor Third (1.2) ratio, 16px base — clear hierarchy without being dramatic
- Colors: Generate from brand blue, warm gray neutral
- Spacing: Base-4 (Tailwind default)
- Dark mode: Full derivation
Example 2: "I need a color palette from this brand color: #6366F1"
- Parse HSL: ~239°, 84%, 67%
- Generate 50–950 scale using the shade generation method
- Map semantic tokens
- Verify WCAG contrast for all text/bg combos
- Output as CSS + Tailwind config
Example 3: "Create a type scale for a blog"
- Ratio: Major Third (1.25) — strong hierarchy for editorial content
- Base: 18px (slightly larger for long-form reading)
- Generate scale with line-height and letter-spacing for each step
