[CSSWG][css-break-4] First Public Draft of CSS Fragmentation Level 4

The CSS WG has published a First Public Working Draft of the
CSS Fragmentation Module Level 4:

     https://www.w3.org/TR/css-break-4/

This module describes the fragmentation model that partitions a flow
into pages, columns, or regions, and provides controls over where
breaking happens. Level 4 is identical to Level 3 except for the new
the 'margin-break' property, which allows control over whether margins
are preserved or truncated at fragmentation breaks, see:
   https://www.w3.org/TR/css-break-4/#break-margins

Note: A related feature being explored is the 'margin-trim' property,
see [css-box-3]: https://www.w3.org/TR/css-box-3/#margin-trim

Please review the draft, and send any comments to the www-style list,
<www-style@w3.org>, prefixed with [css-break-4] (as I did on this
message) or (preferably) file them in the GitHub repository at
   https://github.com/w3c/csswg-drafts/issues

For the CSS WG,
~fantasai