In a print book, one might have a space break between sections, which would typically be a carriage return.
Like this. In an ebook, you could specify this with a margin-top or margin-bottom of 1em.
On the other hand, you might want (and I do want) less space between body text and a block element, such as a block quotation, to show that it's part of the continuing narrative rather than a break in time, setting, or subject. Therefore, I specified a "spacer" tag with a margin-bottom of .7em.
It works fine in Kindle, though not in epub readers, but only if I use something like this:
The problem is, if I run it through the W3 validator, it fails, because there's no closing
tag. But if I add the closing tag, Kindle no longer recognizes the .7em--it treats it as a full 1em carriage return.
I've tried using margin-top instead of margin-bottom, using percentages (both 70%, which actually looked like 700%, and .7%, which was just a carriage return), and adding the !important declaration, none of which worked. The Amazon Kindle Publishing Guide says that Kindle ignores line-height under 120%, so reducing line-height won't help.
So I ask you: is there a way to do this? And if not, do I really need validated HTML? I don't see any requirement for the latter in Amazon's Kindle Guidelines or B&N's Pubit Formatting Guide.