Comment 8 for bug 1886231

I am afraid there is no such thing as a standard delta value. And indeed
calibre doesn't use delta values to decide how to scroll, it uses
deltaMode, https://developer.mozilla.org/en-US/docs/Web/API/WheelEvent/deltaMode

Wheel events from the OS are not consistent across
devices/drivers/versions and platforms. The browser engine used by
calibre converts that mess into a mode, which calibre then uses to
decide how to scroll. Sadly for your mouse the engine thinks the mode
you want is pixel mode. I am fairly sure that there will be some setting
somewhere you can toggel to get your mouse to send events the engine
believes are page or line scroll events, but not having used windows
intwenty years, I cant tell you where that is offhand.