See: http://dev.w3.org/csswg/css-break-3/#break-between "Since breaks are only allowed between siblings, not between a box and its container (see Possible Break Points), a ‘break-before’ value on a first-child box is propagated to its container. Likewise a ‘break-after’ value on a last-child box is propagated to its container. (Conflicting values combine as defined below.) This propagation stops before it breaks through the nearest matching fragmentation context."
Updated link - https://drafts.csswg.org/css-break-3/#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. ..."