CSS WG Blog Last Call for Comments on CSS Sizing Level…

Last Call for Comments on CSS Sizing Level 3

The CSS Working Group has published an updated Working Draft of CSS Intrinsic and Extrinsic Sizing 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 since last year are listed in the changes section 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, to make <input> and <textarea size to fit their contents.
• Deferring the stretch and fit-content keywords to Level 4 (whose focus will be defining these keywords and a contain keyword for aspect-ratio preservation).

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. 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%)?

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 by the CSSWG in 2015 since their syntax was stable and their behavior was tied to behavior exposed in existing CSS2.1 features.)

Please send feedback by either filing an issue in GitHub (preferable) or sending mail to the (archived) public mailing list www-style@w3.org with the spec code ([css-sizing-3]) and your comment topic in the subject line. (Alternatively, you can email one of the editors and ask them to forward your comment.)

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