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[csswg-drafts] [css-backgrounds] Clarify how `border-width` and `border-style` affect `border-image`

From: SelenIT via GitHub <sysbot+gh@w3.org>
Date: Thu, 27 Oct 2016 06:31:17 +0000
To: public-css-archive@w3.org
Message-ID: <issues.opened-185583959-1477549875-sysbot+gh@w3.org>
SelenIT has just created a new issue for 

== [css-backgrounds] Clarify how `border-width` and `border-style` 
affect `border-image` ==
There is a confusion about how `border-width` and `border-style` 
should affect `border-image` (and should they). In the 
[example](http://codepen.io/SelenIT/details/yaAKPZ/) of border-image 
with nonzero `border-image-width` combined with either 
`border-width:0` or `border-style:none`, browsers behave differently. 
Firefox and IE11 renders border-image in all these situation, Edge 14 
— only if `border-style` is not `none`, iOS 10 Safari — only if 
`border-width` is not `0`, and Chrome requires both to render it.

It seems to be a popular assumption that `border-style` _should_ 
override `border-image` (e.g. see the note 1 on the [caniuse.com 
page](http://caniuse.com/#feat=border-image) for `border-image`). 
However, the current spec clearly says that `border-style` and its 
sub-components "set the style of the border, *unless there is a border
 image",* implying that `border-style` shouldn't affect `border-image`
 if its own sub-components values allow it to be rendered.

The test suite for this section (especially tests 
 marks the current behavior of Firefox (i.e. ignoring both 
`border-style:none`and `border-width:0` if there is valid 
`border-image` with explicit non-zero `border-image-width`) as 

But there seems to be a bit of ambiguity in the spec in relation to 
`border-width`. [The 
 for this property has the following remark:

> When the used width of the border is 0, we say that _the border is 

And there is no clarification if it is about just "regular" border or 
about image border, too. Should we add such clarification?

Please view or discuss this issue at 
https://github.com/w3c/csswg-drafts/issues/655 using your GitHub 
Received on Thursday, 27 October 2016 06:31:23 UTC

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