Tailwind CSS v4.3.3 — Release Notes & Engineering Impact

Source available — automated, not human-reviewed

Component: tailwind · Channel: stable. Automated analysis, not a compatibility certification. How this works.

Analysis updated: 2026-10-31.

Compatibility not verified — check source notes

$ npm install --save-exact [email protected]

📄 .MD

🔧 Bug Fixes 6

⚡ Executive Summary (TL;DR)

Tailwind CSS v4.3.3. Source highlight: Support `--watch --poll[=ms]` in `@tailwindcss/cli` when filesystem events are unreliable or unavailable (#20297)

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Who Does This Impact? (Role-Based Analysis)

💻 Software Engineers & Devs

Check the source notes against the package and APIs you use before upgrading.

📊 Product & Engineering Leads

Use the documented changes to assess relevance to your product; release frequency alone is not a quality measure.

⚙️ DevOps & Security

Verify the target version, runtime requirements and rollback procedure in the official documentation.

🔧 Bug Fixes & Patches (6)

Support `--watch --poll[=ms]` in `@tailwindcss/cli` when filesystem events are unreliable or unavailable (#20297)
Canonicalization: match arbitrary hex colors against theme colors case-insensitively (e.g. `bg-[#fff]` and `bg-[#FFF]` → `bg-white`) (#20298)
Prevent Preflight from overriding Firefox's native `iframe:focus-visible` outline styles (#20292)
Ensure `theme('colors.foo')` in JS plugins resolves correctly when both `--color-foo` and `--color-foo-bar` exist (#20299)
Ensure fractional opacity modifiers work with named shadow sizes like `shadow-sm/12.5`, `text-shadow-sm/12.5`, `drop-shadow-sm/12.5`, and `inset-shadow-sm/12.5` (#20302)
Parse selectors like `[data-foo]div` as two selectors instead of one (#20303)

📄 View Raw Release Notes (Original Developer Log)

### Fixed - Support `--watch --poll[=ms]` in `@tailwindcss/cli` when filesystem events are unreliable or unavailable ([#20297](https://github.com/tailwindlabs/tailwindcss/pull/20297)) - Canonicalization: match arbitrary hex colors against theme colors case-insensitively (e.g. `bg-[#fff]` and `bg-[#FFF]` → `bg-white`) ([#20298](https://github.com/tailwindlabs/tailwindcss/pull/20298)) - Prevent Preflight from overriding Firefox's native `iframe:focus-visible` outline styles ([#20292](https://github.com/tailwindlabs/tailwindcss/pull/20292)) - Ensure `theme('colors.foo')` in JS plugins resolves correctly when both `--color-foo` and `--color-foo-bar` exist ([#20299](https://github.com/tailwindlabs/tailwindcss/pull/20299)) - Ensure fractional opacity modifiers work with named shadow sizes like `shadow-sm/12.5`, `text-shadow-sm/12.5`, `drop-shadow-sm/12.5`, and `inset-shadow-sm/12.5` ([#20302](https://github.com/tailwindlabs/tailwindcss/pull/20302)) - Parse selectors like `[data-foo]div` as two selectors instead of one ([#20303](https://github.com/tailwindlabs/tailwindcss/pull/20303)) - Ensure `@tailwindcss/postcss` rebuilds when a preprocessor like Sass changes the input CSS without changing the input file on disk ([#20310](https://github.com/tailwindlabs/tailwindcss/pull/20310)) - Ensure CSS nesting is handled even when Lightning CSS isn't run, such as in `@tailwindcss/browser` and Tailwind Play ([#20124](https://github.com/tailwindlabs/tailwindcss/pull/20124)) - Prevent achromatic theme colors from shifting hue when mixed in polar color spaces like `oklch` ([#20314](https://github.com/tailwindlabs/tailwindcss/pull/20314)) - Ensure `--spacing(0)` is optimized to `0px` instead of `0` so it remains a `<length>` when used in `calc(…)` ([#20319](https://github.com/tailwindlabs/tailwindcss/pull/20319)) - Load `@parcel/watcher` only when needed in `@tailwindcss/cli --watch` mode, so one-off builds and `--watch --poll` work when `@parcel/watcher` can't be loaded ([#20325](https://github.com/tailwindlabs/tailwindcss/pull/20325)) - Use explicit platform fonts instead of `system-ui` and `ui-sans-serif` so CJK text respects the page's `lang` attribute on Windows ([#20318](https://github.com/tailwindlabs/tailwindcss/pull/20318)) - Prevent `@tailwindcss/upgrade` from rewriting ignored files when run from a subdirectory ([#20329](https://github.com/tailwindlabs/tailwindcss/pull/20329)) - Ensure earlier `@source` rules pointing to nested files are scanned when later `@source` rules point to files in parent folders ([#20335](https://github.com/tailwindlabs/tailwindcss/pull/20335)) - Prevent `@tailwindcss/vite` from triggering full page reloads when scanned files are processed by Vite but haven't been loaded as modules yet ([#20336](https://github.com/tailwindlabs/tailwindcss/pull/20336))

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