# Tailwind CSS v4.1.9 — Release & Upgrade Intelligence
- **Product:** Tailwind CSS (https://tailwindcss.com)
- **Version:** v4.1.9
- **Released:** Jun 11, 2025
- **Impact Score:** 5/10
- **Breaking Changes:** Not verified
- **Canonical Analysis:** https://changelogs.us/tailwind/updates/v4.1.9/

## Executive Summary (TL;DR)
Tailwind CSS v4.1.9. Source highlight: Correctly parse custom properties with strings containing semicolons (#18251)

## Bug Fixes
- Correctly parse custom properties with strings containing semicolons (#18251)
- Upgrade: Migrate arbitrary modifiers without percentage signs to bare values (e.g. `/[0.16]` → `/16`) (#18184)
- Upgrade: Migrate CSS variable shorthands where fallback value contains function call (#18184)
- Upgrade: Migrate negative arbitrary values to negative bare values (e.g. `mb-[-32rem]` → `-mb-128`) (#18212)
- Upgrade: Do not migrate `blur` in `wire:model.blur` (#18216)
- Don't add spaces around CSS dashed idents when formatting math expressions (#18220)

## Upgrade Command
```bash
npm install --save-exact tailwindcss@4.1.9
```