# What changed in @vanilla-extract/css

> 4 changes in @vanilla-extract/css 1 from its official release notes, upgrade guides and advisories. Each one cited. Sources checked 2026-10-19. HTML: https://unstale.sh/npm/@vanilla-extract/css/

To see which of these apply to a repository, run `npx @unstale/cli init` in it.

## @vanilla-extract/css 1

### Performance

- The index is built only when a stylesheet needs it, speeding up builds of stylesheets that use only plain class selectors. (1.21.3) — [release notes](https://github.com/vanilla-extract-css/vanilla-extract/releases/tag/%40vanilla-extract/css%401.21.3)

### Fixes and other changes

- In development mode, dots in debug identifiers derived from source file paths are replaced with underscores, preventing CSS selector escaping and instability. Short identifiers are unaffected. (1.21.2) — [release notes](https://github.com/vanilla-extract-css/vanilla-extract/releases/tag/%40vanilla-extract/css%401.21.2)
- Added boxOrdinalGroup to the unitless properties list so numeric values are no longer suffixed with px. (1.21.1) — [release notes](https://github.com/vanilla-extract-css/vanilla-extract/releases/tag/%40vanilla-extract/css%401.21.1)
- Fixed incorrect selector substitution in some style composition cases. (1.21.1) — [release notes](https://github.com/vanilla-extract-css/vanilla-extract/releases/tag/%40vanilla-extract/css%401.21.1)