# Tailwind CSS v4.0.0 — Release & Upgrade Intelligence
- **Product:** Tailwind CSS (https://tailwindcss.com)
- **Version:** v4.0.0
- **Released:** Jan 22, 2025
- **Impact Score:** 5/10
- **Breaking Changes:** Not verified
- **Canonical Analysis:** https://changelogs.us/tailwind/updates/v4.0.0/

## Executive Summary (TL;DR)
Tailwind CSS v4.0.0. Source highlight: ![](https://tailwindcss.com/blog/tailwindcss-v4)

## New Features
- Designed for the modern web — built on cutting-edge CSS features like cascade layers, registered custom properties with `@property`, and `color-mix()`.
- not-* variant — style an element only when it doesn't match another variant, custom selector, or media or feature query.

## Improvements
- New high-performance engine — where full builds are up to 5x faster, and incremental builds are over 100x faster — and measured in microseconds.
- First-party Vite plugin — tight integration for maximum performance and minimum configuration.

## Upgrade Command
```bash
npm install --save-exact tailwindcss@4.0.0
```