[csswg-drafts] [css-flexbox-1][css-position-3] static position of abspos flex children (#5843)

fantasai has just created a new issue for https://github.com/w3c/csswg-drafts:

== [css-flexbox-1][css-position-3] static position of abspos flex children ==
@dholbert pointed out in https://github.com/w3c/csswg-drafts/issues/1432#issuecomment-745549275 https://github.com/w3c/csswg-drafts/issues/1432#issuecomment-746947500 and https://bugzilla.mozilla.org/show_bug.cgi?id=1682641#c9 that the newer CSS Positioned Layout model for handling the alignment properties and the flexbox spec conflict on a few points.

First, overall:
* css-position defines abspos layout as creating an inset-modified containing block (where some of the insets are auto insets derived from the static position), and then applying alignment within that rectangle. It defines the auto offsets for a flex child to coincide with the content edges of its container.
* css-flexbox sets the position of an abspos child more directly in https://drafts.csswg.org/css-flexbox/#abspos-items in normative prose by defining it as the position the item would have had as the sole flex item (but says something different, matching css-position, in the note in the same section).
    
A few places where this matters that @dholbert pointed out:
* Per css-position, in a column flex container, the `align-self` property will apply in the block axis, not the main axis. But per css-flexbox, it will affect the static position in the main axis.
* Per css-position, the `justify-self` property will affect the static position in the inline axis. Per css-flexbox, it can have no effect.
* Per css-position, `justify-content` and `align-content` have no effect on the static position. But per css-flexbox, they do.

We need to resolve these conflicts somehow.


Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/5843 using your GitHub account


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Received on Thursday, 7 January 2021 22:38:51 UTC