Steps to replicate the issue:

• Go to Italian Wikipedia (maybe other wikis have the same issue)
• Enable dark mode
• Enter Piazza Cesare Stovani (one is as good as the other)
• Init a dummy edit
• Click "Pubblica modifiche" (post changes)

What happens?:
The box appear white, so the text is not readable.

What should have happened instead?:
The box should be dark grey.

Other information: