[css-align-3][css-position-3] align-items and justify-items for out of flow items

[alisonmaher]

When an out of flow item is positioned statically in a block/inline formatting context, the spec says to take align-self and justify-self into account.

However, what is expected of align-items and justify-items when set on the originating inline/block parent of the abspos? Normally, align-items and justify-items are the defaults for align-self and justify-self, but in inline layout, align-items and justify-items don't apply in general, and in block layout, align-items doesn't apply to its children. Should abspos elements follow suite and ignore align-items and justify-items if it would have ignored it if it weren't abspos?

I'd assume that we should ignore align-items and justify-items in the same cases for abspos elements such that their static position is as close to what it would have been if not taken out of flow. However, the spec isn't clear on what should happen in this case.

CC @bfgeek

[css-meeting-bot]

The Houdini Task Force just discussed [css-align-3][css-position-3] align-items and justify-items for out of flow items, and agreed to the following:

• RESOLVED: static pos of abspos items ignores place item properties in same context where an actual static pos item ignores them
• RESOLVED: in a static-positioned axis, the alignment property that applies is determined by the writing mode of the parent

The full IRC log of that discussion

<alisonmaher> TabAtkins: the place items prop sets defaults for align self justify self for children but not abspos
<alisonmaher> ...any context it should affect abspos? I say no
<alisonmaher> iank_: that won't be web compat
<alisonmaher> ...everyone suppors align items affecting abs pos
<alisonmaher> ...this will break the internet if we change
<alisonmaher> ...wouldn't be surpised if it would break in grid
<alisonmaher> TabAtkins: are there cases when we should ignore when computing static pos if normal static pos would ignore them
<alisonmaher> ..like align items on block container ?? should static pos of abspos ignore as well
<TabAtkins> s/??/is ignored;/
<alisonmaher> fantasai: align items should affect if static pos and if it would affect if not abspos
<alisonmaher> iank_: fine with that
<alisonmaher> PROPOSED: static pos of abspos items ignores place item properties in same context where an actual static pos item ignores them
<fantasai> PROPOSED: place-items affects abspos children iff they are statically positioned and it would have affected the item if it were not abspos
<alisonmaher> RESOLVED: static pos of abspos items ignores place item properties in same context where an actual static pos item ignores them
<alisonmaher> fantasai: block context with justify items. Parent is horizontal wm, containing block of abspos is vertical, align items prop on parent affects in vert axis, but align self on abspos would normally affect horiz axis because cont if vertical
<alisonmaher> ...in this case it is static pos. Does align self affect horiz or vert direction
<TabAtkins> summary: the abspos's "normal CB" and "abspos CB" have different writing modes.
<alisonmaher> ...or does parent align items affect which direction
<alisonmaher> iank_: Alison filed another issue on this
<alisonmaher> ...maybe was related to flexbox version of this
<alisonmaher> ...I can come up with an answer. Just keep static pos as local as possible. Justify items/self affect the static pos in that axis
<alisonmaher> ...in the parent axis
<oriol> q+
<alisonmaher> fantasai: happy with that
<alisonmaher> TabAtkins: dodn't like it but ok
<alisonmaher> oriol: first find static pos, treat it as if not abspos, against parent. Then when finding final pos treat it as an abpos then base it off of the CBs direction
<alisonmaher> iank_: justify self may resolve in 2 axes
<TabAtkins> This is nonsense, but I'm fine with it because static position is stupid and doesn't matter.
<alisonmaher> ...may be static pos in one axis, and not in the other. So justify self would resolve in both
<fantasai> PROPOSED: in a static-positioned axis, the alignment property that applies is determined by the writing mode of the parent
<alisonmaher> iank_: this happesn with align items in flex
<fantasai> RESOLVED: in a static-positioned axis, the alignment property that applies is determined by the writing mode of the parent