fix: recognize CSS whitespace in named grid areas

[KumJungMin]

Disclosure: I'm a participant of open source contribution program OSSCA

Prerequisites checklist

• I have read the contributing guidelines.

AI acknowledgment

• I did not use AI to generate this PR.
• (If the above is not checked) I have reviewed the AI-generated content before submitting.

What is the purpose of this pull request?

• This PR fixes a false positive that occurs when tabs are used as cell token separators in grid-template-areas.
• According to the CSS Grid specification, consecutive CSS whitespace characters separate cell tokens.
• However, the existing implementation only splits strings on literal spaces (U+0020), causing valid CSS containing tabs to report an unevenGridArea error.

.grid {
    grid-template-areas:
        "a	b"
        "a b";
}

What changes did you make? (Give an overview)

• Added the /[\t\n ]+/u regular expression to match sequences of CSS whitespace.
• Updated grid-template-areas rows to split on CSS whitespace instead of literal spaces.
• Added regression tests covering tabs and combinations of tabs and spaces.
• Used the explicitly defined CSS whitespace characters(tabs, line feeds, and spaces)
• The regular expression was also tested using RegExr.

Related Issues

fixes #537

Is there anything you'd like reviewers to focus on?

Summary by CodeRabbit

• Bug Fixes

  • Improved validation of CSS grid-area definitions with tabs, newlines, spaces, and consecutive whitespace.
  • Correctly identifies uneven grid rows when tab separators are used.

• Tests

  • Added coverage for valid tab-separated grid-area names.
  • Added coverage for invalid uneven rows using tabs.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

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Run ID: 3c7bc40d-083e-4005-8301-86bf97fe6f9d

📥 Commits

Reviewing files that changed from the base of the PR and between 510403e and d9279fe.

📒 Files selected for processing (2)

• src/rules/no-invalid-named-grid-areas.js
• tests/rules/no-invalid-named-grid-areas.test.js

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📝 Walkthrough

Walkthrough

The grid-area rule now treats tabs, newlines, spaces, and repeated whitespace as cell separators. Tests cover valid mixed whitespace and invalid uneven rows.

Changes

Grid Area Whitespace Handling

Layer / File(s)	Summary
CSS whitespace tokenization and validation src/rules/no-invalid-named-grid-areas.js, tests/rules/no-invalid-named-grid-areas.test.js	The parser splits grid-area rows on CSS whitespace sequences. Tests cover tab-separated cells, mixed separators, and uneven row lengths.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to d9279

This localized change makes named grid areas recognize tabs, line feeds, and spaces as CSS whitespace without introducing an actionable merge-blocking risk; it is merge-ready after normal checks and review.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	The changes address issue #537 by splitting grid-area rows on CSS whitespace, including tabs, and add regression tests for tab-separated and uneven rows.
Out of Scope Changes check	✅ Passed	The pull request only changes the affected rule and its related tests. No unrelated changes are present.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 2…
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: recognizing CSS whitespace when parsing named grid areas.

Full details: Docstring Coverage

Explanation

No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 2 files.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[DMartens]

Suggested change

	const cssWhitespace = /[\t\n ]+/u;
	const cssWhitespace = /[\t ]+/u;

CSS in general allows newlines as whitespace but not inside strings (Example)