Originally Posted by Jellby
Great... so how am I to have a forced page break without affecting vertical margins (short of splitting the text in two files)?
I actually think splitting into multiple files is a good solution. Even if you don't want to do it by hand, code to split at page breaks (either via parsing the CSS or just separately-specified @class values) isn't so hard.
Another option is to use padding instead of margins for vertical space you want to be preserved even on the box following a page break.