[Design] Review read-only mode on small screens

Created by: almeidapaulooliveira

Context

Notebook's experience editing on small screens isn't perfect. The team discussed having a read-only mode activated by default on small screens since Blocks don't really make sense in read-only mode.

Notebooks already render a read-only mode for users who do not have edit permissions.

Purposes of design review

• Make sure that that are no inconsistencies in the UX.
• If needed, suggest minor UI improvements.