Tailwind CSS is a utility-first framework that simplifies modern web development by allowing rapid UI creation directly in HTML.
In version 4.0, Tailwind CSS consolidates everything into a single CSS file named global.css or index.css.
A tutorial demonstrates implementing Dark Mode using Tailwind CSS v4.0 with Vite + React, with steps for installation, configuring the Vite plugin, importing Tailwind CSS, and running the app.
Installation involves running 'npm install tailwindcss @tailwindcss/vite', configuring the Vite plugin in the vite.config.js file, importing Tailwind CSS in the main CSS file, and starting the development server with 'npm run dev'.