# Feature catalog — tailwindlabs/tailwindcss > Canonical page: https://codevetter.com/unpack/tailwindcss/feature-catalog # Feature catalog — tailwindlabs/tailwindcss Scanned commit 41d9cae8e53378d16087fcf359eb785c2fd42ce4 (2026-09-08). Generated by codevetter codevetter 1.12.0 on 2026-09-22. User-facing surface is (a) the CSS authoring language — a set of at-rules parsed in `parseCss`, (b) the `tailwindcss` CLI with `build` and `canonicalize` subcommands, (c) five build-tool integrations, (d) a zero-build browser CDN script, and (e) the `@tailwindcss/upgrade` migration CLI. The compat layer additionally re-exposes the entire v3 JS plugin API (`addUtilities`, `matchVariant`, `theme()`, etc.) so existing plugins keep working. IntelliSense-facing APIs (`getClassList`, `getVariants`, `canonicalizeCandidates`) are first-class exports of the design system rather than an afterthought. - The CSS at-rule vocabulary handled in `parseCss` is `@tailwind utilities`, `@utility`, `@source` (with `not`, `inline(…)`, and brace-expansion via `expand()`), `@variant`, `@custom-variant`, `@theme` (with `reference`/`inline`/`default`/`static`/`prefix(…)` options), `@apply`, `@import`, `@plugin`, and `@config`. — [packages/tailwindcss/src/index.ts#L336-L560](https://github.com/tailwindlabs/tailwindcss/blob/41d9cae8e53378d16087fcf359eb785c2fd42ce4/packages/tailwindcss/src/index.ts#L336-L560) [packages/tailwindcss/src/compat/apply-compat-hooks.ts#L54-L90](https://github.com/tailwindlabs/tailwindcss/blob/41d9cae8e53378d16087fcf359eb785c2fd42ce4/packages/tailwindcss/src/compat/apply-compat-hooks.ts#L54-L90) - `@import "tailwindcss" theme(reference)`, `prefix(ident)`, `important`, and `source(…)` are implemented by rewriting the `@media` node that `postcss-import`-style resolution produces — `@media theme(reference)` is transformed into a `context({ reference: true })` wrapper rather than being a distinct parser path. — [packages/tailwindcss/src/index.ts#L455-L540](https://github.com/tailwindlabs/tailwindcss/blob/41d9cae8e53378d16087fcf359eb785c2fd42ce4/packages/tailwindcss/src/index.ts#L455-L540) - The `tailwindcss` CLI exposes `build` (default when no subcommand is given) and `canonicalize`, with root-level `--help` dispatch in `run()` that also errors on unknown non-flag commands. — [packages/@tailwindcss-cli/src/index.ts](https://github.com/tailwindlabs/tailwindcss/blob/41d9cae8e53378d16087fcf359eb785c2fd42ce4/packages/%40tailwindcss-cli/src/index.ts) - `tailwindcss build` supports `--input/-i` (including `-` for stdin), `--output/-o`, `--watch[=always]`, `--poll[=ms]`, `--minify/-m`, `--optimize`, `--cwd`, `--map`, and `--silent`; when no `--input` is given it defaults to compiling `@import 'tailwindcss';`. — [packages/@tailwindcss-cli/src/commands/build/index.ts#L29-L78](https://github.com/tailwindlabs/tailwindcss/blob/41d9cae8e53378d16087fcf359eb785c2fd42ce4/packages/%40tailwindcss-cli/src/commands/build/index.ts#L29-L78) [packages/@tailwindcss-cli/src/commands/build/index.ts#L178-L188](https://github.com/tailwindlabs/tailwindcss/blob/41d9cae8e53378d16087fcf359eb785c2fd42ce4/packages/%40tailwindcss-cli/src/commands/build/index.ts#L178-L188) - `tailwindcss canonicalize` rewrites candidate lists to their canonical form, reading from argv or stdin, with `--css` to point at a design-system entry, `--format text|json|jsonl`, and `--stream` for line-by-line stdin processing — aimed at tooling like Prettier plugins and linters. — [packages/@tailwindcss-cli/src/commands/canonicalize/index.ts#L36-L120](https://github.com/tailwindlabs/tailwindcss/blob/41d9cae8e53378d16087fcf359eb785c2fd42ce4/packages/%40tailwindcss-cli/src/commands/canonicalize/index.ts#L36-L120) [packages/tailwindcss/src/canonicalize-candidates.ts](https://github.com/tailwindlabs/tailwindcss/blob/41d9cae8e53378d16087fcf359eb785c2fd42ce4/packages/tailwindcss/src/canonicalize-candidates.ts) - `@tailwindcss/vite` ships as an array of three Vite plugins — `@tailwindcss/vite:scan` (config capture), `:generate:serve` (dev), and `:generate:build` (production, which additionally runs `optimize()`) — each with `transform.filter` id include/exclude regexes that skip `?raw`, `?url`, `?worker`, and CommonJS proxy requests. — [packages/@tailwindcss-vite/src/index.ts#L166-L285](https://github.com/tailwindlabs/tailwindcss/blob/41d9cae8e53378d16087fcf359eb785c2fd42ce4/packages/%40tailwindcss-vite/src/index.ts#L166-L285) - `@tailwindcss/postcss` accepts `base`, `optimize` (defaults to `NODE_ENV === 'production'`), and `transformAssetUrls`, and bundles a `fixRelativePathsPlugin()` that repairs paths when `postcss-import` ran before it. — [packages/@tailwindcss-postcss/src/index.ts#L52-L84](https://github.com/tailwindlabs/tailwindcss/blob/41d9cae8e53378d16087fcf359eb785c2fd42ce4/packages/%40tailwindcss-postcss/src/index.ts#L52-L84) [packages/@tailwindcss-postcss/src/postcss-fix-relative-paths](https://github.com/tailwindlabs/tailwindcss/blob/41d9cae8e53378d16087fcf359eb785c2fd42ce4/packages/%40tailwindcss-postcss/src/postcss-fix-relative-paths) - `@tailwindcss/webpack` and `@tailwindcss/turbopack` are near-identical webpack `LoaderContext` loaders taking `{ base, optimize }`, both keyed into a shared `QuickLRU` cache of max size 50 via `getCacheKey(resourceId, opts)`. — [packages/@tailwindcss-webpack/src/index.ts#L18-L80](https://github.com/tailwindlabs/tailwindcss/blob/41d9cae8e53378d16087fcf359eb785c2fd42ce4/packages/%40tailwindcss-webpack/src/index.ts#L18-L80) [packages/@tailwindcss-turbopack/src/index.ts#L18-L60](https://github.com/tailwindlabs/tailwindcss/blob/41d9cae8e53378d16087fcf359eb785c2fd42ce4/packages/%40tailwindcss-turbopack/src/index.ts#L18-L60) - `@tailwindcss/browser` is a CDN build that reads `