# Tailwind CSS v4.2.1 — Release & Upgrade Intelligence
- **Product:** Tailwind CSS (https://tailwindcss.com)
- **Version:** v4.2.1
- **Released:** Feb 23, 2026
- **Impact Score:** 5/10
- **Breaking Changes:** Not verified
- **Canonical Analysis:** https://changelogs.us/tailwind/updates/v4.2.1/

## Executive Summary (TL;DR)
Tailwind CSS v4.2.1. Source highlight: Allow trailing dash in functional utility names for backwards compatibility (#19696)

## Bug Fixes
- Allow trailing dash in functional utility names for backwards compatibility (#19696)
- Properly detect classes containing `.` characters within curly braces in MDX files (#19711)

## Upgrade Command
```bash
npm install --save-exact tailwindcss@4.2.1
```