[csswg-drafts] [css-backgrounds-3] `border-image` serialization is inconsistent between browsers (#12854)

AtkinsSJ has just created a new issue for https://github.com/w3c/csswg-drafts:

== [css-backgrounds-3] `border-image` serialization is inconsistent between browsers ==
The [interop view](https://wpt.fyi/results/css/css-backgrounds?label=master&label=experimental&product=chrome&product=firefox&product=safari&aligned&view=interop&q=label%3Ainterop-2023-cssborderimage) for `border-image` looks great, but the serialization tests cheat a bit. For example looking at [this](https://github.com/web-platform-tests/wpt/blob/master/css/css-backgrounds/parsing/border-image-valid.html) WPT test, you see that every case checks for multiple possible serializations, because the major browsers don't agree on what those should be.

For the sake of authors being able to make use of the serialization, and for new browser implementers, it'd be helpful to decide on a single format for serialization.

I know property serialization isn't usually specified explicitly, sticking with the [general principles](https://drafts.csswg.org/cssom/#serializing-css-values) of being brief but unambiguous and in spec order. So I guess I'm just asking for people to agree on what that means here.

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/12854 using your GitHub account


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Received on Thursday, 25 September 2025 09:47:20 UTC