Tailwind CSS v4.0 Released: A High-Performance, CSS-First Rewrite

What happened

Tailwind CSS v4.0 was released on January 22, 2025, according to the official announcement on the Tailwind CSS blog by Adam Wathan. Described as an all-new version optimised for performance and flexibility, it is a ground-up rewrite of the framework with a reimagined configuration and customisation experience that takes advantage of the latest web-platform features.

A high-performance engine

The headline was a new high-performance engine in which full builds are up to 5x faster and incremental builds over 100x faster, measured in microseconds. Tailwind's benchmarks against its Catalyst project showed full builds dropping from 378ms to 100ms and incremental rebuilds with no new CSS completing in around 192 microseconds, over 180x faster. The rewrite leans on modern CSS features including native cascade layers, registered custom properties via @property, and color-mix().

CSS-first configuration

One of the biggest changes was a shift from configuring projects in JavaScript to configuring them in CSS. Instead of a tailwind.config.js file, customisations such as design tokens, custom utilities and variants are defined directly in the CSS file where Tailwind is imported, using an @theme block. All design tokens are also exposed as native CSS variables by default, so values can be referenced anywhere at runtime.

Simplified setup and new capabilities

Installation was streamlined to a single line, @import "tailwindcss", with zero configuration and a first-party Vite plugin. Version 4.0 added automatic content detection that discovers template files without a content array, built-in import support, a modernised P3 color palette using oklch, first-class container queries without a plugin, new 3D transform utilities, expanded radial and conic gradient APIs, @starting-style support for JavaScript-free enter and exit transitions, and a new not-* variant.

Why it mattered

Tailwind CSS v4.0 was a fundamental modernisation of one of the most popular CSS frameworks. By rewriting the engine for dramatic speed gains, moving configuration into CSS, and building on cutting-edge platform features, it reduced setup friction and aligned Tailwind with where the web platform itself was heading.

Related on Skillo

See also: Tailwind CSS v3.3 and its new features.

Sources

• Tailwind CSS v4.0 (official Tailwind blog)

Published date reflects the original event date (2025-01-22). This article is original Skillo editorial written from the sources above; facts were verified in September 2026.