[jhowell]

I did some tests with the Kindle Previewer 3 to see how page-break-avoid is handled in books with enhanced typesetting. Since a large percentage of books sold on Amazon now support ET I think that it's useful to understand. (Looking into how ET works has been my "thing" lately.)

I created a simple EPUB with 10 paragraphs, all with page-break-inside:avoid style, and ran it through the previewer. The ET version broke within different paragraphs as I adjusted the font and size. Looking into the KDF (KFX equivalent) file produced by the previewer I could see that the page-break-inside instruction had been stripped out during ET conversion. If the same holds true in the normal publishing pipeline then using page-break-inside:avoid will have no effect on books rendered with enhanced typesetting.

To test this further I created a KFX file with the same content, but manually added the KFX equivalent of page-break-inside:avoid (break_inside:avoid). When viewed in the previewer this book does not break paragraphs across pages!

However, there is a problem. When the font size is increased to the point where a paragraph can no longer fit on a single page then the previewer fails to display any pages until the font size is decreased. Assuming the same holds true for Kindles, it appears that even if Amazon did translate page-break-inside:avoid to break_inside:avoid for ET books, the result would be problematic.

I have attached my sample EPUB along with the original and non-breaking KFX (azw8) equivalents.