[EuiPopover] Round title and footer corners to match the panel

[ryankeairns]

Closes #9970

Summary

• What: EuiPopoverTitle and EuiPopoverFooter now use the same corner radius as the popover panel.
• Why: Fixes [EuiPopoverFooter] Footer background is not clipped to the popover panel border radius #9970. A title or footer background currently squares off the panel corners. This gets more obvious once panel radius increases.
• How: Apply border.radius.medium to the title’s top corners and the footer’s bottom corners. Do not add overflow: hidden on the panel — that clips the filter-based shadow and arrow.

API Changes

None.

Screenshots

Before	After

Impact Assessment

Note: Most PRs should be tested in Kibana to help gauge their Impact before merging.

• 🔴 Breaking changes — What will break? How many usages in Kibana/Cloud UI are impacted?
• 💅 Visual changes — Title/footer fills now follow the panel radius. Visible when those regions have a background (e.g. Kibana options list EuiInputPopover). No layout or API change.
• 🧪 Test impact — May break functional or snapshot tests (e.g., HTML structure, class names, default values).
• 🔧 Hard to integrate — If changes require substantial updates to Kibana, please stage the changes and link them here.

Impact level: 🟢 Low

Release Readiness

• Documentation: N/A — visual bugfix, no docs change
• Figma: N/A
• Migration guide: N/A
• Adoption plan (new features): N/A

QA instructions for reviewer

• Open Storybook EuiPopoverFooter and EuiPopoverTitle.
• Give EuiPopoverFooter (and EuiPopoverTitle) a background color.
• Bottom corners of the footer follow the panel radius (not square).
• Top corners of the title follow the panel radius (not square).
• Filter shadow and arrow still render (no clipping).
• Repeat on Layout / EuiInputPopover with a footer background, including panelPaddingSize="none".

Checklist before marking Ready for Review

• Filled out all sections above
• QA: Tested light/dark modes, high contrast, mobile, Chrome/Safari/Edge/Firefox, keyboard-only, screen reader
• QA: Tested in CodeSandbox and Kibana
• QA: Tested docs changes N/A
• Tests: Existing Jest snapshots still pass (class names unchanged)
• Changelog: Added changelog entry
• Breaking changes: Added breaking change label (if applicable) N/A

Reviewer checklist

• Approved Impact Assessment — Acceptable to merge given the consumer impact.
• Approved Release Readiness — Docs, Figma, and migration info are sufficient to ship.

[Copilot]

🟢 Approval recommended

The change is a low-risk, self-contained styling adjustment that aligns title/footer visuals with the existing panel radius (only a minor comment wording nit noted).

Pull request overview

Updates EuiPopoverTitle and EuiPopoverFooter styling so their backgrounds respect the same corner radius as the popover panel, preventing title/footer fills from visually “squaring off” rounded panel corners (per #9970).

Changes:

• Applied euiTheme.border.radius.medium to the title’s top corners.
• Applied euiTheme.border.radius.medium to the footer’s bottom corners.
• Added an upcoming changelog entry documenting the visual bugfix.

File summaries

File	Description
packages/eui/src/components/popover/popover_title.styles.ts	Rounds the title’s top corners to match the popover panel radius.
packages/eui/src/components/popover/popover_footer.styles.ts	Rounds the footer’s bottom corners to match the popover panel radius.
packages/eui/changelogs/upcoming/9985.md	Documents the popover title/footer radius bugfix in the changelog.

Review details

• Files reviewed: 3/3 changed files
• Comments generated: 1
• Review effort level: Lite

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[mgadewoll]

🟢 Changes are LGTM. Thanks for the fix!

[infra-vault-gh-plugin-prod]

💚 Build Succeeded

• Buildkite Build
• Commit: 54e563e
• Documentation website
• Storybook
• ✅ Visual regression tests passed

History

• 💚 Build #5186 succeeded 54e563e
• 💚 Build #5185 succeeded 4b91b6f
• 💚 Build #5184 succeeded 4b91b6f

[infra-vault-gh-plugin-prod]

💚 Build Succeeded

• Buildkite Build
• Commit: 54e563e

History

• 💚 Build #7774 succeeded 4b91b6f