Prevent Document Download

Does anyone know if there's a way to stop users from downloading files?

The use case is that we want staff / applicants to be able to read staff handbooks etc - but not be able to download them (preventing them from getting into the wrong hands). I've been able to hide the Download link on the viewer in CSS:

.kn-file-download {
visibility: hidden;

Which works fine (although I couldn't work out how to make this specific to one view). But there's also a right click menu on the view which I can't work out how to disable.

Any ideas?