Remove Box usage from Storybook stories and tests

[mperrotti]

Relates to https://github.com/github/primer/issues/5425 and https://github.com/github/primer/issues/5422

Changelog

New

Changed

Removed

Rollout strategy

• Patch release
• Minor release
• Major release; if selected, include a written rollout or migration plan
• None; if selected, include a brief description as to why
  • No release needed - these are just stories and tests

Testing & Reviewing

Merge checklist

• Added/updated tests
• Added/updated documentation
• Added/updated previews (Storybook)
• Changes are SSR compatible
• Tested in Chrome
• Tested in Firefox
• Tested in Safari
• Tested in Edge
• (GitHub staff only) Integration tests pass at github/github (Learn more about how to run integration tests)

[changeset-bot]

⚠️ No Changeset found

Latest commit: 66b200a

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[github-actions]

👋 Hi, this pull request contains changes to the source code that github/github depends on. If you are GitHub staff, we recommend testing these changes with github/github using the integration workflow. Thanks!

[Copilot]

Pull Request Overview

This PR removes the usage of the deprecated Box component from Storybook stories and tests throughout the codebase. The changes replace Box components with native HTML elements (div, form, etc.) or more appropriate semantic alternatives like Stack, while maintaining the same styling using CSS modules or inline styles.

Key Changes:

• Replaces Box components with semantic HTML elements and CSS modules for styling
• Migrates Box-based layouts to use the Stack component where appropriate for flexible layouts
• Updates imports to remove Box and add necessary styling alternatives

Reviewed Changes

Copilot reviewed 42 out of 42 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
packages/react/src/stories/useFocusTrap.stories.tsx	Replaced Box layout components with Stack and div elements, added CSS module for styling
packages/react/src/stories/useAnchoredPosition.stories.tsx	Converted Box-based positioning to native div elements with CSS modules
packages/react/src/stories/deprecated/SideNav.dev.stories.tsx	Replaced Box styling with inline CSS custom properties
packages/react/src/stories/ThemeProvider.stories.tsx	Migrated Box containers to div elements with CSS module classes
packages/react/src/experimental/SelectPanel2/	Updated multiple story files to use shared CSS modules instead of Box styling
packages/react/src/TreeView/	Replaced Box containers with div elements and CSS modules
packages/react/src/TextInput/TextInput.dev.stories.tsx	Changed Box form containers to semantic form elements
packages/react/src/Portal/	Migrated Box styling to CSS modules with clsx for conditional classes
packages/react/src/Overlay/	Extensive replacement of Box layouts with CSS modules and semantic elements
Various test files	Updated test components to use semantic HTML instead of Box

[github-actions]

size-limit report 📦

Path	Size
packages/react/dist/browser.esm.js	88.64 KB (0%)
packages/react/dist/browser.umd.js	88.73 KB (0%)

[mperrotti]

Updating the rest of the snapshots because the diffs were very minor spacing things that have no impact outside of Storybook.