Widgets editor: Block appender does not appear as full width

[noisysocks]

Description

The block appender in the Widgets screen appears as a small button to the right of the widget area. It should expand to fill the widget area.

You could potentially use git bisect to find what commit broke this.

Step-by-step reproduction instructions

1. Activate a classic theme.
2. Go to Appearance → Widgets.
3. Look at the block appender at the bottom of any widget area.

Screenshots, screen recording, code snippet

You can see what the appender button should look like when there are no blocks in the widget area:

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

[itsmingjie]

Hi! I'm one of the program coordinators of a nonprofit program called CodeDay Init, and we partner with colleges to help CS students make their first open-source contribution.

We'll claim this issue for now and a group of students will be on it soon with mentorship! If this issue is no longer relevant, please let me know.

[noisysocks]

Thanks @itsmingjie! The issue is still relevant. Let me know if you need help or extra info.

[upluke]

@noisysocks Hi, my group is working on this issue. We think we're located the styling on this issue. It seems it's part of wordPress issue instead gutenberg issue. Is it possible this might be the case?

[noisysocks]

Hello! The code that implements this is in the edit-widgets package, which is in the Gutenberg repo. WordPress imports this package which is how it ends up there.

https://github.com/WordPress/gutenberg/blob/trunk/packages/edit-widgets/