Re: [css-background] Add the *-x/y longhands to appropriate properties?

On Mon, Apr 21, 2014 at 6:41 PM, Brad Kemper <brad.kemper@gmail.com> wrote:
> On Apr 21, 2014, at 10:44 AM, "Tab Atkins Jr." <jackalmage@gmail.com> wrote:
>>> OK, so I guess 'bg-pos-y:start' would get mapped to 'bg-pos-y:top' and to 'bg-pos-block:start' once you knew the mode was horizontal-tb. Right?
>>
>> Well, it would just get mapped to "bg-pos-y: top;".  No need to map it
>> into the other property, since they're aliases.
>
> Not sure if you are sitting hairs between "mapping" vs. "aliasing",

Splitting hairs between computed values and aliasing.

> but my point was that it is only an alias once you know the mode is horizontal-tb, no? Otherwise, if(!horizontal) y != block.

"bg-pos-y: start" isn't a shorthand for anything else, but it does
turn into "bg-pos-y: top" (or bottom) depending on w-m/direction.

bg-pos-y is then also an alias for either bg-pos-inline or
bg-pos-block, depending on w-m/direction.

~TJ