# Tailwind CSS v4.0.4 — Release & Upgrade Intelligence
- **Product:** Tailwind CSS (https://tailwindcss.com)
- **Version:** v4.0.4
- **Released:** Feb 06, 2025
- **Impact Score:** 5/10
- **Breaking Changes:** Not verified
- **Canonical Analysis:** https://changelogs.us/tailwind/updates/v4.0.4/

## Executive Summary (TL;DR)
Tailwind CSS v4.0.4. Source highlight: Fix a crash when setting JS theme values to `null` (#16210)

## Bug Fixes
- Fix a crash when setting JS theme values to `null` (#16210)
- Ensure escaped underscores in CSS variables in arbitrary values are properly unescaped (#16206)
- Ensure that the `containers` JS theme key is added to the `--container-*` namespace (#16169)
- Ensure theme `@keyframes` are generated even if an `--animation-*` variable spans multiple lines (#16237)
- Vite: Skip parsing stylesheets with the `?commonjs-proxy` flag (#16238)
- Fix `order-first` and `order-last` for Firefox (#16266)

## Upgrade Command
```bash
npm install --save-exact tailwindcss@4.0.4
```