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[css-flexbox] Clarify whether unresolvable percentages prevent stretching? #4312
Description
https://drafts.csswg.org/css-flexbox/#valdef-align-items-stretch
If the cross size property of the flex item computes to auto, and neither of the cross-axis margins are auto, the flex item is stretched
Combined with:
https://drafts.csswg.org/css2/visudet.html#the-height-property
the height of the containing block is not specified explicitly (i.e., it depends on content height), and this element is not absolutely positioned, the value computes to 'auto'.
So I just wanted to verify that the item should still stretch in a case like this:
<div style="display: flex;">
<div style="height: 100%; background: green"></div>
<div style="height: 200px;"></div>
<div>Note that neither Chrome nor Firefox currently stretch the item.
Activity
Loirooriol commentedon Sep 16, 2019
An indefinite percentage only behaves as auto, but doesn't actually compute to auto. That's just legacy prose from css2. See https://drafts.csswg.org/css-sizing-3/#behave-auto
davidsgrogan commentedon Sep 16, 2019
The Note in https://drafts.csswg.org/css-sizing-3/#behave-auto says
Does that mean that https://drafts.csswg.org/css-flexbox/#valdef-align-items-stretch should change from
to
Which would bring us back to the original question?
Loirooriol commentedon Sep 16, 2019
I believe the flexbox prose is not legacy so it really means "computes to auto".
For example https://drafts.csswg.org/css-flexbox/#min-size-auto uses the new terminology: "percentages calculated against this size will behave as auto"
cbiesinger commentedon Jan 23, 2020
Per #4525 indefinite percentages do not count as auto and thus should not stretch the item.