UnoCSS
Atomic CSS engine — Tailwind-compatible syntax but 10× faster. Anthony Fu (Vue/Nuxt core team), 2021.
On-demand: scans source code, generates only classes actually used. Presets for Tailwind, Wind (variant), Mini (smaller), Icons (inline SVG from Iconify). Vite-first but works with Webpack, Rollup, Astro. Hyperactive community since 2023. Better Vue/Nuxt DX than Tailwind directly. Competitor: Tailwind v4 Oxide engine cut the speed lead in 2025.