W3c/csswg-drafts

W3c/css-houdini-drafts

This repository contains the official editor's drafts for the CSS Houdini specifications, which define a set of low-level APIs that give developers direct access to the CSS engine's internals. These specifications enable developers to extend CSS with new features, create custom layout and painting behaviors, and improve performance through more efficient styling techniques. ## Key Features - **Paint API** — Allows developers to programmatically generate images for CSS properties like `background-image` and `border-image` using JavaScript. - **Layout API** — Enables the creation of custom layout modes that can be used in CSS, providing alternatives to Flexbox and Grid. - **Animation Worklet** — Provides a performant way to create scroll-linked and other high-performance animations that run off the main thread. - **Properties and Values API** — Allows registration of custom CSS properties with type checking, default values, and inheritance behavior. - **Typed OM** — Exposes CSS values as typed JavaScript objects rather than strings, improving performance and developer ergonomics. ## Philosophy Houdini aims to make CSS more extensible by providing developers with the same low-level capabilities that browser engineers use to implement CSS features, enabling innovation while maintaining performance and compatibility.