You could use padding instead of margin, which is not discarded at pagebreaks. Or you could have empty pagebreak elements thus:
Code:
<p class="poetry">Third line of the poem</p>
<div class="pagebreak"></div>
<p class="poetry">First line of the poem</p>
and define:
Code:
div.pagebreak {
page-break-before: always;
height: 0;
margin: 0;
padding: 0;
}