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 66.x, generated at 2026-01-28.
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 |
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 |