For now in 5k resolution book index looks small and can be scaled, book itself has alot of space around the text and text is also small ( which can be fixed with default font size, but its not convinient usually just Ctrl+scroll works much better), but its possible to do book a bit adaptive it has enough space it can open more then 2 pages at once( very useful for tech books), and on scale hide text. Probably also some magnify glass feature will be good.
For now in 5k resolution book index looks small and can be scaled, book itself has alot of space around the text and text is also small ( which can be fixed with default font size, but its not convinient usually just Ctrl+scroll works much better), but its possible to do book a bit adaptive it has enough space it can open more then 2 pages at once( very useful for tech books), and on scale hide text. Probably also some magnify glass feature will be good.