Re: [CSSWG] Minutes Telecon 2013-03-27

On Wed, Mar 27, 2013 at 6:15 PM, fantasai <fantasai.lists@inkedblade.net>wrote:

>   - RESOLVED: We copy the behaviour of % margins/paddings from grid to
>               flexbox: they are relative to their respective dimension,
>               not always the inline dimension (as in block layout)
>
> Flexbox
> -------
>
>   Topic: vertical % margins and padding on flexbox
>   <glazou> http://lists.w3.org/Archives/**Public/www-style/2013Mar/0143.**
> html <http://lists.w3.org/Archives/Public/www-style/2013Mar/0143.html>
>   <glazou> http://lists.w3.org/Archives/**Public/www-style/2013Mar/**
> thread.html#msg143<http://lists.w3.org/Archives/Public/www-style/2013Mar/thread.html#msg143>
>   dbaron: Not necessarily /from/ me, but I wanted to poke the issue
>   dbaron: People are shipping implementations of flexbox and this is a
>           change proposal.
>   dbaron: I'm curious about the status
>
>   fantasai: When you have margins on a block element, the vert margins
>             (block direction margins), they resolve against the size of
>             the container in the inline dimension
>   fantasai: Flexbox doesn't say anything about this being different for
>             flex items, whereas grid does specify that % margins are
>             relative to the same dimension
>   fantasai: so there's an inconsistency
>
>   fantasai: For blocks, height of containing block typically isn't defined,
>             so % margins relative to that would fall to zero.
>   fantasai: Resolving against the containing block width gives better
>             behavior in the common cases there.
>   fantasai: However for flexbox that reasoning doesn't apply so much
>             (nor for grid). These layout models are frequently used
>             with a defined height.
>   <fantasai describes flexbox behaviour>
>   fantasai: Another issue is that the inconsistency in dimensions is
>             particularly confusing for Flexbox: e.g. for row flexboxes
>             percentage margins would work in the main axis, but for
>             column flex boxes they wouldn't.
>
>   glazou: Implementors?
>   dbaron: I'm fine with switching, but it seems odd for different display
>           types to behave differently.  I'd prefer to do it sooner rather
>           than later though.
>   Rossen: Matching flexbox behaviour to grid makes sense, will help app
>           developers
>   Rossen: The inconsistency will be overcome by authors soon enough.
>   RESOLVED: We copy the behaviour of % margins/paddings from grid to
> flexbox
>

Was not supporting % margins/paddings on both grid and flexbox considered?
It seems to me a mistake that we support them on blocks, but it's a mistake
we're stuck with.