UnoCSS Strict Design Preset

A strict design system preset for UnoCSS.

Features

• 🎨 Enforces usage of theme values for colors, spacing, font sizes, and more
• 🚫 Blocks arbitrary values (e.g., text-[20px], m-[10px])
• ✨ Ensures consistent class naming conventions
• 🎯 Perfect for maintaining design system consistency

Design Philosophy

This preset is built on the principle that consistent design systems lead to better user experiences and more maintainable codebases. Key principles include:

1. Intentional Constraints: By limiting to predefined theme values, we ensure design consistency across your entire application.

2. No Magic Numbers: Arbitrary values often lead to design inconsistencies. All values should come from your theme configuration.

3. Predictable Patterns: Class names follow consistent patterns, making your code more readable and maintainable.

4. Design System First: Forces teams to think in terms of design systems rather than one-off solutions.

Installation

# Using npm
npm install -D unocss-preset-strict-design

# Using yarn
yarn add -D unocss-preset-strict-design

# Using pnpm
pnpm add -D unocss-preset-strict-design

Usage

Add the preset to your UnoCSS configuration:

// uno.config.ts
import { defineConfig } from 'unocss'
import { presetStrictDesign } from 'unocss-preset-strict-design'

export default defineConfig({
  presets: [
    presetStrictDesign({
      theme: {
        colors: {
          // Your color palette
          primary: '#0066cc',
          // ...
        },
        spacing: {
          // Your spacing scale
          '1': '0.25rem',
          // ...
        },
        text: {
          // Your font sizes (optionally with line height / letter spacing)
          sm: { fontSize: '0.875rem', lineHeight: '1.25rem' },
          base: { fontSize: '1rem' },
          // ...
        },
        fontWeight: {
          // Your font weights
          normal: '400',
          // ...
        },
        opacity: {
          // Your opacity values
          '50': '0.5',
          // ...
        },
      },
    }),
  ],
})

Sizing Resolves from Spacing

Sizing utilities (w-*, h-*, min-w-*, min-h-*, max-w-*, max-h-*, and gap-*) resolve directly from theme.spacing. There are no separate width/height/minWidth/minHeight/maxWidth/maxHeight theme sections — define your sizes once in spacing and they work for spacing and sizing utilities alike.

Restrictions

This preset enforces several restrictions to maintain design consistency:

1. Theme Values Only: All properties must use predefined theme values

   • ❌ text-[20px], m-[10px], bg-[#fff] — arbitrary bracket values are always blocked
   • ✅ text-sm, m-4, bg-primary — allowed when the key exists in your theme (theme.text.sm, theme.spacing['4'], theme.colors.primary)

   A utility resolves only when its key is defined in the matching theme section. Numeric or size-suffixed values without a theme entry are blocked (e.g. p-5 is blocked unless theme.spacing['5'] exists), and utilities outside the strict theme sections (e.g. rounded-lg, shadow-md) are always blocked.

2. Consistent Class Names: Enforces consistent naming conventions

   • ❌ color-red, fw-bold
   • ✅ text-red, font-bold

3. Required Theme Properties: The theme configuration must include:

   • colors
   • spacing
   • text
   • fontWeight

   opacity is optional at creation, but the opacity-* utilities only resolve values defined there.

Available Utility Classes

This preset provides the following utility classes:

Mask Size

• mask-size-{size}: Sets the mask size using your theme's spacing values
  • Example: mask-size-4 will use the spacing value defined at theme.spacing['4']
  • Only uses predefined spacing values from your theme

Opacity

• opacity-{value}: Sets the opacity using your theme's opacity values
  • Example: opacity-50 will use the opacity value defined at theme.opacity['50']
  • Only uses predefined opacity values from your theme
  • This overrides the opacity rule in the wind4 preset that allows for arbitrary opacity values

Migrating from v2 to v3

v3 rebases the preset from presetWind3 to presetWind4 (the Tailwind 4-compatible preset). The following changes affect your configuration and generated CSS.

1. fontSize is now text

The flat fontSize theme section was replaced by wind4's nested text section. Each entry is an object with a required fontSize and optional lineHeight / letterSpacing.

Flat string values:

// v2
fontSize: {
  sm: '0.875rem',
}

// v3
text: {
  sm: { fontSize: '0.875rem' },
}

Tuple values (v2 accepted [fontSize, lineHeight] tuples):

// v2
fontSize: {
  sm: ['0.875rem', '1.25rem'],
}

// v3
text: {
  sm: { fontSize: '0.875rem', lineHeight: '1.25rem' },
}

There is no compatibility shim — TypeScript will error on the old fontSize key.

2. New base preset and peer requirement

The preset is now built on presetWind4 instead of presetWind3, and the peer dependency is unocss ^66.7.0. Bump your unocss dependency together with this preset.

3. Removed width/height theme sections

The width, height, minWidth, minHeight, maxWidth, and maxHeight theme sections no longer exist (in v2 they inherited from spacing unless overridden). Sizing utilities (w-*, h-*, min-*, max-*, gap-*) now resolve from theme.spacing directly — define your sizes there.

4. Size suffixes now work when your theme defines them

In v2, size-suffixed utilities (-xs, -sm, -md, ... -9xl) were always blocked. In v3 they resolve when the corresponding key exists in your theme section: text-sm works if theme.text.sm exists, p-sm works if theme.spacing.sm exists, and both are blocked otherwise. The suffix list also covers wind4's new 2xs and 3xs sizes. Utilities outside the strict theme sections (rounded-lg, shadow-md, ...) remain always blocked.

5. Generated CSS looks different

wind4 emits CSS-variable-based output and preflights: theme values become CSS variables (e.g. --spacing-1, --colors-primary, --text-sm-fontSize) and declarations reference them. Visual results are unchanged when values come from your theme, but raw CSS diffs are expected.

Also note that v3 closes blocking holes v2 had: bracket values such as w-[10px], gap-[2rem], mx-[10px], py-[4px], and mask-size-[10px] slipped through v2's regexes and are now blocked, so you may see new block behavior for classes that previously (incorrectly) generated CSS.

6. The defineConfig generic still works

The preset factory is exported typed against PresetStrictDesignTheme, so defineConfig<PresetStrictDesignTheme>(...) compiles in v3 exactly as it did in v2 — no config change needed. A bare defineConfig({ ... }) also infers the strict theme from the preset, so custom rules, shortcuts, and extendTheme entries in your uno.config see theme.opacity and the required-fontSize text typing automatically.

Annotating the theme value is still the recommended authoring pattern — it applies the required nested text shape checking (and the compile error on the old flat fontSize) right where the theme is written:

const theme: PresetStrictDesignTheme = {
  // ...
}

export default defineConfig({
  presets: [presetStrictDesign({ theme })],
})