It would be really helpful to have a toggle in the settings that allows users to turn off the default margins when viewing PDFs in horizontal (landscape) mode.

At the moment, horizontal view automatically adds greyed-out margins on either side of the document, which reduces the amount of space available for writing or annotating. This isn't the case in vertical mode, where the document fills the screen edge-to-edge.

Having the option to disable these margins would:

Maximize the usable screen area

Make PDFs easier to annotate or edit

Provide a cleaner, distraction-free full-screen view

For users working on small screens or needing more space, this would be a significant improvement.