fix: recognize CSS whitespace in named grid areas

[KumJungMin]

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

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• 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 CSS grid-area validation for tabs, spaces, and consecutive whitespace between area names.
  • Correctly identifies uneven grid rows when tabs are used as separators.
  • Newline-separated tokens are no longer interpreted as whitespace by the validator.

• Tests

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

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

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📝 Walkthrough

Walkthrough

The grid-area rule now treats tabs and repeated spaces as separators between cell tokens. Tests cover mixed separators and uneven rows with tab-separated cells.

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 consecutive tabs and spaces. Tests cover valid mixed whitespace and invalid uneven rows.

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

Merge Risk: ⚪ Minimal · up to 4fe7b

The grid-area parser now accepts tab and repeated-space separators, preventing false uneven-cell-count reports for valid templates. No current merge-readiness risk remains.

Suggested reviewers: pixel998

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the primary change: recognizing CSS whitespace in named grid areas.
Linked Issues check	✅ Passed	The changes address issue #537 by parsing tabs and spaces as separators between grid-area cell tokens. The added tests cover tab-separated valid rows and uneven rows with tabs.
Out of Scope Changes check	✅ Passed	All changes are limited to the grid-area parser and regression tests required by issue #537. 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…

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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)

[KumJungMin]

Thanks for pointing this out :) (https://regexr.com/8ocse)

I've removed \n from the pattern. ea057db