Margin is a Mac app for studying dense PDF textbooks without separating reading from note-taking. It keeps questions and explanations beside the source text while leaving the original PDF unchanged, so returning to a difficult idea starts with the work already done.

What's included in this release:

• Readers can place questions and explanations inline beside selectable PDF text without modifying the original file.
• A visual note map previews saved thoughts and returns the reader directly to the relevant passage.
• Topic scratchpads gather notes from different pages into a writing space or Excalidraw canvas for synthesis.
• Bookmarks, reading positions, notes, and scratchpads stay locally on the Mac and work without an account.
• Exported workspace backups help readers preserve or move their study material while keeping source PDFs in place.

Together, inline context, passage-level navigation, scratchpads, and local storage create a focused study loop that is easy to resume across long technical books.