Support for double hyphenation across line breaks (typographic convention)

[ap175]

Specification: CSS Text Module (Level 3/4)

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Problem

In some typographic traditions (notably Polish and German), when a word is hyphenated at a line break, a hyphen is shown both at the end of the first line and at the beginning of the next line.

Example:

Bogoryja-
-Zakrzewski

This differs from the current behavior in CSS, where hyphens: auto inserts a hyphen only at the end of the broken line:

Bogoryja-
Zakrzewski

Currently, there is no way in CSS to enable this typographic convention.

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Use case

This feature is relevant for:

• high-quality typography (e.g. digital publishing, e-books, editorial layouts)
• languages where this convention is used (e.g. Polish, German)
• multi-column justified text, where hyphenation plays an important role in spacing

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Proposed solution

Introduce a new property (or extend existing ones) to control hyphen rendering across line breaks.

For example:

hyphens: auto;
hyphenate-character: "-";
hyphenate-style: double;

Where:

• hyphenate-style: single (default) → current behavior

• hyphenate-style: double → adds a hyphen at both:

  • end of the broken line
  • beginning of the next line

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Alternative approaches

This could also be implemented as:

• an extension of hyphenate-character
• a new value in hyphens
• or a separate property controlling line-start markers after hyphenation

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Additional considerations

• Should respect lang attribute (e.g. lang="pl", lang="de")

• Should integrate with existing hyphenation dictionaries

• Needs to define behavior for:

  • column layout (column-count)
  • inline elements
  • line wrapping and reflow

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Why this matters

The current CSS model does not fully support established typographic conventions used in print. Adding this feature would improve the quality of text layout on the web, especially for languages with stricter typographic standards.

This is not only about hyphenation itself, but about the inability to render markers on both sides of a fragmentation boundary (line break).

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References

• Polish typographic rules for hyphenation
• German typography conventions (Duden)
• Czech typographic rules for hyphenation

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Thanks for considering this feature.