Adjacent items with text decoration should be separated by a small gap

[r12a]

This issue is applicable to Chinese and Japanese.

When two underlined items appear side-by-side, the underline should be broken between the two. For example, although there are no gaps between characters in the code stream, there should be small visible gaps in the underlining of this example, which contains 2 proper nouns ('sòng', and 'ōuyángxiū') and a poem title ('míng fēi qū').

More:

• Clreq
• example

The GAP

None of the major browsers show this gap between text decorations.

css-text-decor-4 The CSS Text specification currently proposes the use of a text-decoration-skip-inset property, although it is not yet finalised and is not supported by any browser. The auto value should automatically produce the slightly shorter line lengths below the characters.

Gecko, Blink, and Webkit

Priority

These text decorations are used commonly in Chinese text, and decorations that run into each other creates readability problems. This gap is therefore being labelled as basic.

Tests & results

Interactive test, text-decoration-skip-inset: auto; will create a gap between words that are side by side and underlined using the u tag.
Interactive test, text-decoration-skip-inset: auto; will create a gap between spans that are side by side and underlined using text-decoration-line:underline.

Action taken

Awaiting finalisation of CSS syntax.

Outcomes

tbd

[r12a]

The first comment in this issue contains text that will automatically appear in one or more gap-analysis documents as a subsection with the same title as this issue. Any edits made to that comment will be immediately available in the Editor's draft of the document. Proposals for changes or discussion of the content can be made by adding comments below this point.

Relevant gap analysis documents include: Chinese • Japanese

[xfq]

There's a typo in the example: 莫歐陽修明妃曲 should be 宋歐陽修明妃曲. 莫 means 'do not', while 宋 means Song.

[kidayasuo]

From JLReq TF meeting on 2024-2-6: Two adjacent underlines are hard to distinguish by nature and therefore such a usage should be avoided. It is not seen with printed books. JLReq TF thinks the improvement is desired but not critical.

[xfq]

This is more of a Chinese usage. IIUC Japanese generally does not use underlines to indicate proper nouns.

[xfq]

In the case of "dynasty + person's name", two proper nouns often appear together, like the example in https://github.com/w3c/clreq/issues/502#issuecomment-1751628253