perf(BaseStyles): Remove expensive :has([data-color-mode]) selectors #7325
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Remove :has([data-color-mode]) selectors that scanned the entire DOM on every style recalculation. Input color-scheme is already handled by global selectors. Part of #7312
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Pull request overview
This PR removes performance-impacting CSS selectors from BaseStyles that were causing expensive DOM traversals during style recalculation. The removed :has([data-color-mode]) selectors scanned the entire DOM tree unnecessarily, as the input color-scheme functionality is already handled by existing global selectors elsewhere in the codebase.
Key Changes:
- Removed redundant
:has([data-color-mode='light'])and:has([data-color-mode='dark'])selectors - Added explanatory comment documenting why the selectors were removed and where the functionality is handled
- Added changeset documenting the performance improvement
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| packages/react/src/BaseStyles.module.css | Removed expensive :has() selectors and replaced with explanatory comment |
| .changeset/perf-basestyles-has-selector.md | Added changeset documenting the performance optimization |
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joshblack
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👋 Hi from github/github-ui! Your integration PR is ready: https://github.com/github/github-ui/pull/9374 |
Summary
Remove expensive
:has([data-color-mode])selectors that scanned the entire DOM on every style recalculation.Changes
Removed redundant CSS rules that used
:has([data-color-mode='light'])and:has([data-color-mode='dark'])selectors. Input color-scheme is already handled by global selectors in the codebase.Expected INP Impact
Why this matters
These were the most expensive selectors in the entire codebase:
:has([data-color-mode])on the root element forces a full DOM traversalThis single change likely has the highest INP impact of all the optimizations.
Part of the INP performance optimization effort. See #7312 for full context.