Child parent break propagation with break-before page
According to the specification:
3.1.1. Child→Parent Break Propagation Since breaks are only allowed between siblings, not between a box and its container (see Possible Break Points), break values applied to children at the start/end of a parent are propagated to the parent, where they can take effect.
If I understand correctly it means that we should not add a blank page before the first section in this document: break-before-child-parent-propagation.html
<main> <section> <h2>Section 1</h2> <p>This is a paragraph.</p> </section> </main>
The break-before is only allowed between siblings but
<section> has not sibling. So we should not break between
<section> and its container