The **css‑shorthand‑properties** library provides a ready‑made list of every CSS shorthand name and the longhand properties it expands to, collected from W3C specifications. It exposes a small API (`isShorthand` and `expand`) for developers—both in Node (via npm) and in browsers—to check whether a property is a shorthand and to retrieve its constituent longhand properties, optionally recursing for nested shorthands like `border`. This is useful for tooling, linting, or any code that needs to programmatically work with CSS property expansion.