/unocss

UnoCSS Variants

Variants apply modifications to utility rules, like hover:, dark:, or responsive prefixes.

How Variants Work

When matching hover:m-2:

1. hover:m-2 is extracted from source
2. Sent to all variants for matching
3. hover: variant matches and returns m-2
4. Result m-2 continues to next variants
5. Finally matches the rule .m-2 { margin: 0.5rem; }
6. Variant transformation applied: .hover\:m-2:hover { margin: 0.5rem; }

Creating Custom Variants

variants: [
  // hover: variant
  (matcher) => {
    if (!matcher.startsWith('hover:'))
      return matcher
    return {
      // Remove prefix, pass to next variants/rules
      matcher: matcher.slice(6),
      // Modify the selector
      selector: s => `${s}:hover`,
    }
  },
],
rules: [
  [/^m-(\d)$/, ([, d]) => ({ margin: `${d / 4}rem` })],
]

Variant Return Object

• matcher - The processed class name to pass forward
• selector - Function to customize the CSS selector
• parent - Wrapper like @media, @supports
• layer - Specify output layer
• sort - Control ordering

Built-in Variants (preset-wind3)

Pseudo-classes

• hover:, focus:, active:, visited:
• first:, last:, odd:, even:
• disabled:, checked:, required:
• focus-within:, focus-visible:

Pseudo-elements

• before:, after:
• placeholder:, selection:
• marker:, file:

Responsive

• sm:, md:, lg:, xl:, 2xl:
• lt-sm: (less than sm)
• at-lg: (at lg only)

Dark Mode

• dark: - Class-based dark mode (default)
• @dark: - Media query dark mode

Group/Peer

• group-hover:, group-focus:
• peer-checked:, peer-focus:

Container Queries

• @container, @sm:, @md:

Print

• print:

Supports

• supports-[display:grid]:

Aria

• aria-checked:, aria-disabled:

Data Attributes

• data-[state=open]:

Dark Mode Configuration

Class-based (default)

presetWind3({
  dark: 'class'
})

<div class="dark:bg-gray-800">

Generates: .dark .dark\:bg-gray-800 { ... }

Media Query

presetWind3({
  dark: 'media'
})

Generates: @media (prefers-color-scheme: dark) { ... }

Opt-in Media Query

Use @dark: regardless of config:

<div class="@dark:bg-gray-800">

Custom Selectors

presetWind3({
  dark: {
    light: '.light-mode',
    dark: '.dark-mode',
  }
})

CSS @layer Variant

Native CSS @layer support:

<div class="layer-foo:p-4" />

Generates:

@layer foo {
  .layer-foo\:p-4 { padding: 1rem; }
}

Breakpoint Differences from Windi CSS

Media Hover (Experimental)

Addresses sticky hover on touch devices:

<div class="@hover-text-red">

Generates:

@media (hover: hover) and (pointer: fine) {
  .\@hover-text-red:hover { color: rgb(248 113 113); }
}