[CSSWG][css-sizing-3] Updated WD of Sizing, Last Call for Comments
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2018-03-04 12:37:08 UTC
The CSS WG has published an updated Working Draft of the
CSS Intrinsic and Extrinsic Sizing Module Level 3:


This module extends the CSS sizing properties with keywords that
represent content-based "intrinsic" sizes and context-based
"extrinsic" sizes, allowing CSS to more easily describe boxes
that fit their content or fit into a particular layout context.

Significant changes are listed at:
and include
* merging in the full definitions of all sizing properties
from CSS2.1 (min/max?-width/height) and css-ui (box-sizing)
* more thorough definition of replaced element intrinsic sizes
and percentage sizing within indefinite containers
* defining min-content and max-content to work on form controls
* deferring the 'stretch' and 'fit-content' keywords to Level 4
(whose focus will be defining these keywords and 'contain')

Open issues include:
* Adding more illustrations (help wanted)
* Working out how calc() values including percentages work
on margins/padding/width/height/gaps when the container size
depends on this child box’s size (input wanted)
That is, currently when we are calculating the size of the
container we treat a percentage size as zero. Then once
the size of the container is established, we resolve the
percentage against that size. What should happen if we have
a size as calc(20% + 10px)? Do we ignore the 10px or honor
it in some way? What about calc(10px - 20%)?
See https://github.com/w3c/csswg-drafts/issues?q=is%3Aopen+is%3Aissue+label%3Acss-sizing-3
for all open issues.

We expect to transition to CR soon, so this draft effectively
marks the beginning of a last call for comments period; we
will be accepting comments at least through the end of March,
and depending on the state of the draft, aim to transition to
CR sometime in April. (We will of course process comments
during CR as well, but would prefer to get them sooner rather
than later.)

(Note that the min-content and max-content keywords have already
been officially cleared for shipping prior to CR by the CSSWG
since their syntax was stable and their behavior was tied to
behavior exposed in existing CSS2.1 features.)

Please review the draft, and send any comments to this mailing list,
<www-***@w3.org>, prefixed with [css-sizing] (as I did on this
message) or (preferably) file them in the GitHub repository at

For the CSS WG,