Right now:
It works like that regardless if "Continuous" mode is on or off.
This is not how any software I known scrolls, and it is very unintuitive. The point of a "Continuous" modes of all sorts is that, on a screen, users often find the page abstraction unnecessary. Our screen is our page. And we don't want the page breaks of the original media to interfere with our scrolling.
May I kindly suggest that when "Continuous" is enabled, Page Up/Down will scroll by the height of the screen rather than the height of the page. Space/Shift+Space would probably do the same thing in this mode (i.e. get rid of the snapping).
Thank you for your software!