develop

[srobinson]

• fix: migrate to @eslint/css-tree to support CSS variables (var())

  • Replace css-tree with @eslint/css-tree v3.6.6
  • Add var() detection to skip validation for CSS custom properties
  • Update all imports across 8 files
  • Fix TypeScript types for walk() callbacks
  • Remove @types/css-tree dependency

  Resolves issue where properties containing var() would report validation
  errors even though expansion was successful. CSS variables are runtime
  values that cannot be validated at parse time.

• docs: update bundle sizes and dependencies in README

  • Update bundle size: ~68KB (ESM), ~73KB (CJS) minified + brotli
  • Remove css-tree from installation (now bundled dependency)
  • Update test count: 973 tests
  • Update acknowledgments to @eslint/css-tree
  • Add accurate performance metrics

• docs: update comment to reference @eslint/css-tree

• docs: link to b_values fork in acknowledgments

• docs: add separate acknowledgment for b_values

  • Keep @eslint/css-tree link to upstream repo
  • Add b_values link for CSS value expansion/validation work

[Copilot]

Pull Request Overview

This PR migrates the CSS parsing dependency from css-tree to @eslint/css-tree and adds support for CSS variables (var() functions) which cannot be validated at parse time.

Key Changes

• Replaced css-tree with @eslint/css-tree v3.6.6 across all source files
• Added containsVar() function to detect and skip validation of properties containing CSS variables
• Updated TypeScript types for walk() callbacks from csstree.Value to csstree.CssNode with type guards
• Changed package dependency from peer to bundled, updated README installation instructions accordingly

Reviewed Changes

Copilot reviewed 11 out of 12 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/internal/layer-parser-utils.ts	Updated import and walk callback types with type guard
src/internal/is-value-node.ts	Updated type import to @eslint/css-tree
src/handlers/transition/transition-layers.ts	Updated import and walk callback types with type guard
src/handlers/mask/mask-layers.ts	Updated import and walk callback types with type guard
src/handlers/grid/expand.ts	Updated import and walk callback types with type guard
src/handlers/background/background-layers.ts	Updated import and walk callback types with type guard
src/handlers/animation/animation-layers.ts	Updated import and walk callback types with type guard
src/core/validate.ts	Updated import, added containsVar() function and validation skip logic
pnpm-lock.yaml	Updated dependencies from css-tree@3.1.0 to @eslint/css-tree@3.6.6 with mdn-data@2.23.0
package.json	Changed css-tree from peerDependency to bundled dependency @eslint/css-tree
docs.llm/llm_src.txt	Updated imports across all code sections (with one comment needing correction)
README.md	Updated bundle sizes, installation instructions, test counts, and acknowledgments

Files not reviewed (1)

• pnpm-lock.yaml: Language not supported

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[Copilot]

The comment still references "css-tree library" but should be updated to "@eslint/css-tree" to match the migration.

Suggested change

	* CSS variables cannot be validated by css-tree as they are runtime values.
	* CSS variables cannot be validated by @eslint/css-tree as they are runtime values.