[Om-singhaI]

What changed / motivation ?

transformValue turns a numeric style value into a string and asks getNumberSuffix what unit to append. getNumberSuffix falls back to px when the key is not in unitlessNumberProperties and has no entry in numberPropertySuffixes. fontSizeAdjust was in neither, so fontSizeAdjust: 0.545 compiled to font-size-adjust:.545px. font-size-adjust takes a plain number, so the browser drops the declaration and the property does nothing.

The Flow type for this property is 'none' | number, so a number is what users are told to write. A string like '0.545' does compile to valid CSS, because strings never reach getNumberSuffix, but Flow rejects it. Dynamic styles already emit the value unitless through a custom property, so static and dynamic styles produced different CSS for the same input.

• Added fontSizeAdjust to unitlessNumberProperties in shared/utils/transform-value.js, next to fontWeight.
• Extended the existing unitless case in transform-value-normalization-test.js with fontSizeAdjust: 0.545, the same way [babel-plugin] fix unitless zoom bug #1346 extended it with zoom: 2.

Same shape of fix as #1346 for zoom and #705 for the grid properties.

Linked PR/Issues

Fixes #1902

Additional Context

Only fontSizeAdjust changes. No other key moves in or out of the set, and no existing snapshot changed.

Testing, all measured on this branch against main at 20f2a50 with Node 25.6.1 and jest 30.1.3, run from packages/@stylexjs/babel-plugin:

• npx jest __tests__/transform-value-normalization-test.js: 1 suite, 18 tests passed, 19 snapshots passed.
• npx jest __tests__/transform-value-normalization-test.js __tests__/transform-stylex-create-test.js: 2 suites, 118 tests passed, 217 snapshots passed.
• npx jest src/shared/utils/__tests__: 3 suites, 28 tests passed.
• npx jest __tests__/transform-stylex-keyframes-test.js __tests__/transform-stylex-props-test.js __tests__/validation-stylex-create-test.js: 3 suites, 141 passed, 58 skipped, 113 snapshots passed.
• Negative control: with transform-value.js restored from main and the new test kept, npx jest __tests__/transform-value-normalization-test.js gives 1 failed and 17 passed, and the snapshot diff reads .x1v6sj9q{font-size-adjust:.545} against .xq0srfb{font-size-adjust:.545px}.
• prettier 3.5.3 --check and eslint 8.57.1 are clean on both changed files.
• The repro from the issue now prints .x1v6sj9q{font-size-adjust:.545} where it printed .xq0srfb{font-size-adjust:.545px} before.
• fontSizeAdjust: 0.545 and fontSizeAdjust: '0.545' now compile to the same rule, .x1v6sj9q{font-size-adjust:.545}. 0 still gives font-size-adjust:0, 'none' still gives font-size-adjust:none, and the dynamic form still gives font-size-adjust:var(--x-fontSizeAdjust).

Pre-flight checklist

• I have read the contributing guidelines
  Contribution Guidelines
• Performed a self-review of my code

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[Copilot]

Copilot review overview

🟢 Approval recommended

No unresolved issues were identified.

Review effort: Lite
Findings: None

What changed in this PR

Fixes Babel plugin normalization so numeric fontSizeAdjust values compile as unitless CSS.

Changes:

• Registers fontSizeAdjust as unitless.
• Adds regression coverage for generated CSS.

File	Description
packages/​@stylexjs/​babel-plugin/​src/​shared/​utils/​transform-value.js	Treats fontSizeAdjust numbers as unitless.
packages/​@stylexjs/​babel-plugin/​__tests__/​transform-value-normalization-test.js	Verifies unitless CSS output.

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