Description

In the resizable editor, if there is little content, the vertical scrollbar is not necessary, but it seems to always be displayed.

After investigating this issue, I found that it was caused by the top border added by #66041.

Step-by-step reproduction instructions

• Open the site editor.
• Open the pattern or template part editor.

Screenshots, screen recording, code snippet

If I temporarily disable the top border this issue doesn't occur:

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