[LiamSarsfield]

Proposed changes

Share the modern Settings well background, border, radius, and padding through a Sass mixin. The Except panel, Critical CSS status, Image CDN controls, and LCP status retain their existing selectors and markup.

A mixin needs fewer call-site edits than a ModuleSubsection variant: each existing SCSS block includes it without changing React components. The Except panel passes null padding because its toggle and expanded content already own their padding.

Related product discussion/links

None.

Does this pull request change what data or activity we track or use?

No.

Testing instructions

Enable the modern Boost dashboard and Image CDN premium controls. Compare Settings at widths 1280 and 782 in LTR and RTL, with Except and image quality panels collapsed and expanded. Switch back to the legacy dashboard and repeat.

Both production builds passed. Both compiled sheets are byte-identical (SHA-256):

• jetpack-boost.css: bad2513e68e526fa6fe15c5e4668b7ca8f55fcee8034ce6429b5b7e9881f748b
• jetpack-boost.rtl.css: 83941619fded67e30ddf3716460f61ea9af822a92cb1288bfd539a4dd4f8b9fb

All 16 raw rendered HTML comparisons match, including all eight legacy cases. These establish no change to the rendered markup or styles.

Fourteen screenshot pairs match pixel-for-pixel. Two expanded modern RTL captures show capture noise: 30 pixels at width 1280 and 5 at width 782. Diff images are retained as diff-modern-1280-rtl-expanded.png and diff-modern-782-rtl-expanded.png in the validation evidence.

Six focused Jest suites (38 tests) and Stylelint passed. Boost e2e specs could not run in this checkout; the Docker browser pass supplies the rendering evidence.

[github-actions]

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[jp-launch-control]

Code Coverage Summary

This PR did not change code coverage!

That could be good or bad, depending on the situation. Everything covered before, and still is? Great! Nothing was covered before? Not so great. 🤷

Full summary · PHP report · JS report

[xavier-lc]

LGTM