[noruzzamans]

Trac ticket: https://core.trac.wordpress.org/ticket/66427
Gutenberg PR: WordPress/gutenberg#82817

Description

Allows valid CSS custom property references (such as var(--wp--preset--spacing--32)) in wp_sanitize_block_gap_value().

When a theme defines a preset block gap in theme.json (such as styles.spacing.blockGap: "var:preset|spacing|32"):

1. wp_get_global_styles() resolves the preset to its CSS variable format: var(--wp--preset--spacing--32).
2. Candidate values for the global block gap in layout rendering are passed through wp_sanitize_block_gap_value().
3. Because wp_sanitize_block_gap_value() disallows parentheses to prevent CSS injection, the resolved preset was rejected and returned null.
4. As a result, Grid layout calculations in wp_get_layout_style() fell back to 0.5em instead of using the theme's preset gap value.
5. In Grid blocks with columnCount and minimumColumnWidth, columns stack into a single column.

Testing Instructions

1. Run PHPUnit test suite:

   npm run test:php -- tests/phpunit/tests/block-supports/layout.php

2. Verify all tests pass including CSS variable preset sanitization and grid layout fallback.

[github-actions]

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs.

Core Committers: Use this line as a base for the props when committing in SVN:

Props noruzzaman.

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[github-actions]

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[tellthemachines]

LGTM!

[github-actions]

A commit was made that fixes the Trac ticket referenced in the description of this pull request.

SVN changeset: 65212
GitHub commit: f01d3b9

This PR will be closed, but please confirm the accuracy of this and reopen if there is more work to be done.