UnoCSS is an instant atomic CSS engine designed to be flexible and extensible. The core is un-opinionated - all CSS utilities are provided via presets. It's a superset of Tailwind CSS, so you can reuse your Tailwind knowledge for basic syntax usage.
Important: Before writing UnoCSS code, agents should check for uno.config.* or unocss.config.* files in the project root to understand what presets, rules, and shortcuts are available. If the project setup is unclear, avoid using attributify mode and other advanced features - stick to basic class usage.
The skill is based on UnoCSS v66.10.5, generated at 2026-09-25.
Core
| Topic | Description | Reference |
|---|---|---|
| Configuration | Config file setup and all configuration options | core-config |
| Rules | Static and dynamic rules for generating CSS utilities | core-rules |
| Shortcuts | Combine multiple rules into single shorthands | core-shortcuts |
| Theme | Theming system for colors, breakpoints, and design tokens | core-theme |
| Variants | Apply variations like hover:, dark:, responsive to rules | core-variants |
| Extracting | How UnoCSS extracts utilities from source code | core-extracting |
| Safelist & Blocklist | Force include or exclude specific utilities | core-safelist |
| Layers & Preflights | CSS layer ordering and raw CSS injection | core-layers |
| Processors | Transform generated CSS layers (incl. Lightning CSS) | core-processors |
Presets
Main Presets
| Topic | Description | Reference |
|---|---|---|
| Preset Wind3 | Tailwind CSS v3 / Windi CSS compatible preset (most common) | preset-wind3 |
| Preset Wind4 | Tailwind CSS v4 compatible preset with modern CSS features | preset-wind4 |
| Preset Mini | Minimal preset with essential utilities for custom builds | preset-mini |
Feature Presets
| Topic | Description | Reference |
|---|---|---|
| Preset Icons | Pure CSS icons using Iconify with any icon set | preset-icons |
| Preset Attributify | Group utilities in HTML attributes instead of class | preset-attributify |
| Preset Typography | Prose classes for typographic defaults | preset-typography |
| Preset Web Fonts | Easy Google Fonts and other web fonts integration | preset-web-fonts |
| Preset Tagify | Use utilities as HTML tag names | preset-tagify |
| Preset Rem to Px | Convert rem units to px for utilities | preset-rem-to-px |
Transformers
| Topic | Description | Reference |
|---|---|---|
| Variant Group | Shorthand for grouping utilities with common prefixes | transformer-variant-group |
| Directives | CSS directives: @apply, @screen, theme(), icon() | transformer-directives |
| Compile Class | Compile multiple classes into one hashed class | transformer-compile-class |
| Attributify JSX | Support valueless attributify in JSX/TSX | transformer-attributify-jsx |
Integrations
| Topic | Description | Reference |
|---|---|---|
| Vite Integration | Setting up UnoCSS with Vite and framework-specific tips | integrations-vite |
| Nuxt Integration | UnoCSS module for Nuxt applications | integrations-nuxt |