Grid items should only stretch the inline direction for justify-self:stretch but items that were blockified and became block frames stretch regardless of justify-self value because that's the default behaviour for block frames in the inline direction (until they also support the css-align properties). So, for a grid item with a 'justify-self' value other than 'stretch' we need to trigger shrink-wrap behavior on its block frame when we reflow it.

Comment on attachment 8687313 [details] [diff] [review] fix Review of attachment 8687313 [details] [diff] [review]: ----------------------------------------------------------------- Just one nit on the commit message: > Bug 1224634 - [css-grid] Grid items should only stretch the inline direction for justify-self:stretch. r=dholbert The application of "only" here is ambiguous & easy to misread. I initially read this as "only stretch the inline direction [i.e. not block direction]", which confused me. Really, you mean "only... for justify-self:stretch. [not other justify-self values]" Please reword to avoid this ambiguity. One possible rewording: > Bug 1224634 - [css-grid] Make grid items shrink-wrap when > measuring their size, unless they have justify-self:stretch. r=dholbert (or whatever you think)

Comment on attachment 8687315 [details] [diff] [review] test tweaks Review of attachment 8687315 [details] [diff] [review]: ----------------------------------------------------------------- ::: layout/reftests/css-grid/grid-col-max-sizing-max-content-001.html @@ +17,5 @@ > grid-auto-columns: minmax(min-content,max-content); > border: dashed blue; > float:left; > clear:left; > + justify-items: stretch; Why do we need to add this declaration in all of these tests? "justify-items: auto" (the default) should compute to "stretch" on a grid already, according to https://drafts.csswg.org/css-align-3/#propdef-justify-items. Maybe I'm misreading something, though? Or, does that not work correctly right now?

> Why do we need to add this declaration in all of these tests? Not really no. I figured I should have some 'justify-items: stretch' and some 'justify-self: stretch' just for testing. I'll remove one the declarations here so we test the 'auto' behavior too.

OK, sounds good.

https://hg.mozilla.org/integration/mozilla-inbound/rev/2906aec76e64 https://hg.mozilla.org/integration/mozilla-inbound/rev/5e66054666ac

https://hg.mozilla.org/mozilla-central/rev/2906aec76e64 https://hg.mozilla.org/mozilla-central/rev/5e66054666ac