Editor Sidebar: Scrollable tab layout appears broken on Windows

[t-hamano]

Description

The Tabs component becomes scrollable when it overflows its container width.

This behavior appears to work correctly in Storybook on Windows OS:

However, in the editor sidebar, the layout appears broken when tabs overflow. Below is a screenshot of what it looks like when you access Site Editor > Navigation in Japanese:

This layout looks "broken" to me for two reasons:

• The tabs are pushed up.
• The scrollbar overlaps the bottom border of the header.

Step-by-step reproduction instructions

• Switch to Japanese locale and access the navigation menu.
• Alternatively, you can recreate this issue on other screens by changing the text length in your browser developer tools.

Screenshots, screen recording, code snippet

No response

Environment info

No response

Please confirm that you have searched existing issues in the repo.

• Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

• Yes

Please confirm which theme type you used for testing.

• Block
• Classic
• Hybrid (e.g. classic with theme.json)
• Not sure