Just noticed Tailwind 4 has been released:

Tailwind CSS v4.0 is an all-new version of the framework optimized for performance and flexibility, with a reimagined configuration and customization experience, and taking full advantage of the latest advancements the web platform has to offer.

• New high-performance engine — where full builds are up to 5x faster, and incremental builds are over 100x faster — and measured in microseconds.
• Designed for the modern web — built on cutting-edge CSS features like cascade layers, registered custom properties with @property, and color-mix().
• Simplified installation — fewer dependencies, zero configuration, and just a single line of code in your CSS file.
• First-party Vite plugin — tight integration for maximum performance and minimum configuration.
• Automatic content detection — all of your template files are discovered automatically, with no configuration required.
• Built-in import support — no additional tooling necessary to bundle multiple CSS files.
• CSS-first configuration — a reimagined developer experience where you customize and extend the framework directly in CSS instead of a JavaScript configuration file.
• CSS theme variables — all of your design tokens exposed as native CSS variables so you can access them anywhere.
• Dynamic utility values and variants — stop guessing what values exist in your spacing scale, or extending your configuration for things like basic data attributes.
• Modernized P3 color palette — a redesigned, more vivid color palette that takes full advantage of modern display technology.
• Container queries — first-class APIs for styling elements based on their container size, no plugins required.
• New 3D transform utilities — transform elements in 3D space directly in your HTML.
• Expanded gradient APIs — radial and conic gradients, interpolation modes, and more.
• @starting-style support — a new variant you can use to create enter and exit transitions, without the need for JavaScript.
• not-* variant — style an element only when it doesn’t match another variant, custom selector, or media or feature query.
• Even more new utilities and variants — including support for color-scheme, field-sizing, complex shadows, inert, and more.

Anyone used it yet?

There’s a PragProg book on Tailwind (Modern CSS with Tailwind Book Club!) are there any other Tailwind learning resources worth a look?