Originally Posted by _savage
There's only one stylesheet in my book, and it contains these settings:
/* widows: 0; */
/* orphans: 0; */
I used to have a "width:100%;" and "height:100%;" in it as well, but I removed that as per above discussion.
If I understand you correctly then I should add a "height:100%;" to the single pseudo-fixed-layout page (the one with the dedication, for exampe). This would ensure a correct vertical centering of that page's content.
Ensure is too strong a term. As far as I can tell, iBooks seems to sometimes ignore this (because of an underlying WebKit bug; I filed a bug about it yesterday). However, I would say that it increases the probability
of the reader getting it right.
Also, you should not be setting the margins to zero on normal, flowing pages. I've seen some readers (Kobo on iOS) break when I do that. YMMV. As a rule, you should avoid styling the HTML and BODY tags (beyond possibly setting fonts) unless you're doing something very unusual, such as the aforementioned special single-page layouts.