Re: [csswg-drafts] [css-backgrounds-4] Align logical values for <position> with the ones defined in CSS Logical Properties (#549)

Okay, here's my proposal for an updated `<position>` that allows logical keywords:

```
<position> = [
  [ left | center | right | x-start | x-end ] || [ top | center | bottom | y-start | y-end ]
|
  [ left | center | right | x-start | x-end | <length-percentage> ]
  [ top | center | bottom | y-start | y-end | <length-percentage> ]?
|
  [ [ left | right | x-start | x-end ] <length-percentage> ] &&
  [ [ top | bottom | y-start | y-end ] <length-percentage> ]
|
  [ block-start | block-end | center ] || [ inline-start | inline-end | center ]
|
  [ start | end ]{2}
|
  [ [ block-start | block-end ] <length-percentage> ] &&
  [ [ inline-start | inline-end ] <length-percentage> ]
]
```

The logical additions are:

1. You can use a one or two logical keywords, or the full 4-value form with logicals.
2. To make it easier to refer to corners, you can specify a pair of `start`/`end` keywords. (So you don't have to write out the full `block-start inline-end`, just `start end` instead.)
3. The *mixed* keywords (`x-start`, etc) are added to the list of physical keywords, specifying a physical axis and then a logical direction within that axis.
4. Using one logical keyword works the same as using one physical keyword - the opposite axis is "center".

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Received on Wednesday, 24 May 2023 16:33:22 UTC