# Tailwind CSS v4.0.9 — Release & Upgrade Intelligence
- **Product:** Tailwind CSS (https://tailwindcss.com)
- **Version:** v4.0.9
- **Released:** Feb 25, 2025
- **Impact Score:** 5/10
- **Breaking Changes:** Not verified
- **Canonical Analysis:** https://changelogs.us/tailwind/updates/v4.0.9/

## Executive Summary (TL;DR)
Tailwind CSS v4.0.9. Source highlight: Make JS APIs available to plugins and configs in the Standalone CLI (#15934)

## Bug Fixes
- Make JS APIs available to plugins and configs in the Standalone CLI (#15934)
- Vite: Don't crash when importing a virtual module from JavaScript that ends in `.css` (#16780)
- Fix an issue where `@reference "…"` would sometimes omit keyframe animations (#16774)
- Ensure `z-*!` utilities are properly marked as `!important` (#16795)
- Read UTF-8 CSS files that start with a byte-order mark (BOM) (#16800)
- Ensure nested functions in selectors used with JavaScript plugins are not truncated (#16802)

## Upgrade Command
```bash
npm install --save-exact tailwindcss@4.0.9
```