[csswg-drafts] [css-text-decor-5] Allow percentages in `text-decoration-trim` (#8403)

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

== [css-text-decor-5] Allow percentages in `text-decoration-trim` ==
There was already some discussion in #4557 around allowing to use percentage values in `text-decoration-trim`.

One relatively common use case is to animate an underline from no width to its normal size when hovering a link. I saw this on several sites, lately, though I didn't save the URLs, unfortunately. Nontheless, here's an example for this effect:
https://www.landkreis-regensburg.de/buergerservice/bauen/bauamt/

Another one is to partially underline a headline based on its width.

The main question regarding this feature was to what the percentage values relate to.
@fantasai initially defined them to be [relative to the width of the containing block for block containers and relative to the total length of the untrimmed line decoration for inline elements](https://github.com/w3c/csswg-drafts/issues/4557#issuecomment-1117735704).
As decorations don't extend to the edges of a block container, I argued that decoration and text lenghts would be disconnected with that definition. My suggestion was to [let them refer to the width of each fragment of the decoration box or the total length of the untrimmed line decoration of the in-flow inline-level children](https://github.com/w3c/csswg-drafts/issues/4557#issuecomment-1117950076).
@jfkthame and @litherum then mentioned that referring to the fragment widths might also not be the best approach and mentioned issues regarding [short fragments vs. long fragments](https://github.com/w3c/csswg-drafts/issues/4557#issuecomment-1176014387) and [bidi runs](https://github.com/w3c/csswg-drafts/issues/4557#issuecomment-1176744075).
@dbaron then [noted](https://drafts.csswg.org/css-break/#break-decoration) that this might be controlled via [`box-decoration-break`](https://drafts.csswg.org/css-break/#break-decoration).

Sebastian

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/8403 using your GitHub account


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Received on Monday, 6 February 2023 13:15:06 UTC