The designers of eBooks can't seem to figure how to consistently use and kind of inline formatting tags (span, em, etc.).
I've seen books with something like the following:
Code:
<p>“They <em>knew.”</em></p>
<p>“But <em>how</em>?”</p>
Later, there'd be a wrap of the question mark and the quotes:
Code:
<p>“And <em>now?”</em></p>
I don't know if there are any rules about what should get wrapped by the
<em>, but pick a standard and stick to it in the same book.