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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
🦋 Changeset detectedLatest commit: cb9f9c9 The changes in this PR will be included in the next version bump. This PR includes changesets to release 1 package
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👋 Hi, this pull request contains changes to the source code that github/github-ui depends on. If you are GitHub staff, test these changes with github/github-ui using the integration workflow. Or, apply the |
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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 |
👋 Hi from github/github-ui! Your integration PR is ready: https://github.com/github/github-ui/pull/9543 |
| /* Global styles for dark mode */ | ||
| &:has([data-color-mode='dark']) { | ||
| input & { |
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Afaik these selectors wouldn't work anyway?
Since this is a child base style inside an input - which wouldn't be valid, since I inputs are self closing
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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.