(In reply to Daniel Holbert [:dholbert] from comment #0)
But based on my notes in my above-linked github comment, I think the spec changed to say these properties don't impact the abspos child's static position, and we need to update our implementation accordingly.
Hmm -- actually, if Chrome is to be trusted (and I'm not sure it is), then there may be something a bit more subtle here...
I had initially just noticed that Chrome entirely "fails" the first above-linked test (fully ignoring
align-content for positioning abspos children in a flex container), but they basically pass the second test -- they honor
justify-content when dealing with abspos flex children, except for the fact that they trip over the
end values per https://bugs.chromium.org/p/chromium/issues/detail?id=1011718
We honor both (with 'align-content' being honored IFF the flex container is multi-line). Our implementation here is grounded in Flexbox section 4.1, https://drafts.csswg.org/css-flexbox/#abspos-items , which says:
The static position of an absolutely-positioned child of a flex container is determined such that the child is positioned as if it were the sole flex item in the flex container, assuming both the child and the flex container were fixed-size boxes of their used size
I had mistakenly thought this spec-text had been removed, but apparently it has not! Taken directly, this spec-text means the flex container's
align-content value should be honored when determining the static pos of its abspos children (though only if it's a multi-line flex container, in the case of
align-content.) But Chrome doesn't seem to do that, at least for align-content; and I can't find any spec text that directly states what the effect of justify-content is supposed to be on a flex container's abspos children. https://drafts.csswg.org/css-align-3/#distribution-flex would the most authoritative section, and that spec-text just talks about regular flex items, and doesn't mention abspos children static-position at all (whereas the section on the *-self properties has a whole section about effects on abspos elements).
fantasai, I've managed to confuse myself about what the spec is asking for here. Perhaps you can help? :)
The short version of my question is basically: Is flexbox section 4.1 (https://drafts.csswg.org/css-flexbox-1/#abspos-items , quoted above in this bug-comment) still meant to be authoritative in its implications about
align-content having an impact on the static position of abspos flex children? (And if so, does the css-align spec need to be adjusted to make that impact clearer, perhaps?)