There were several issues with the book, including an improper cover definition, which of course is unrelated to the black screens. I haven't looked at the CSS yet, but I'll take Kovid at his word. As I said to begin with, "Crap in, crap out." This was a sloppy book to convert and the results were expected. i respectfully disagree with Kovid on the stricter markup required for KF8 as far as the opf goes.