Skip to content

Fix and refactor UnderlineNav to resolve CLS issues and improve performance/code quality #7622

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
iansan5653 merged 2 commits into from
Mar 4, 2026
Merged

Fix and refactor UnderlineNav to resolve CLS issues and improve performance/code quality #7622

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
807e04e
Initial plan
Copilot Mar 4, 2026
984b15d
Add changeset for UnderlineNav CSS overflow refactor
Copilot Mar 4, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
5 changes: 5 additions & 0 deletions .changeset/underline-nav-css-overflow.md
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
---
"@primer/react": minor
---

Refactors `UnderlineNav` overflow handling to use CSS-based overflow detection instead of JavaScript width measurements, eliminating layout shift (CLS) issues and improving performance. The overflow menu is now implemented with `ActionMenu`, and item registration uses a descendant registry instead of the `React.Children` API. Consumer-facing changes: items can now be wrapped in fragments or wrapper components; the current item may appear in the overflow menu when the viewport is narrow; and the overflow menu button is right-aligned.