This sample is a traditional book originally designed with InDesign which was then converted to a fixed width EPUB3.
Click the link above to view the book in an HTML5 player.
Click the image above to view the book in an HTML5 player. Please note that the width of the open book is fixed at 900px. Smaller viewports will need to decrease browser magnification.
Below are screen shots from the EPUB when it was hosted on Apple Books.