Liquid scaling makes the book scale to fill 100% of the viewer window. If you resize the window, the book should resize as well.
Zooming disables liquid scaling. To re-enable it, match the book size to the window.
Normally, liquid scaling will be applied as soon as the book is loaded. Use
book@zoominit to override this behavior, and set a manual initial zoom level.
To disable liquid scaling permanently, set
book@zoomliquidscaling to false.