Allow Preview to use a note’s content language (`lang`) independently of UI language (proper hyphenation)

Feature requests
1

Title: Allow Preview to use a note’s content language (lang) independently of UI language (proper hyphenation)

Use case or problem

I keep Obsidian’s UI language in English, but I often write notes in German (also de-CH, sometimes FR/ES). In Preview, justified text relies on:

.markdown-preview-section p { text-align: justify; hyphens: auto; }

However, hyphenation is only reliable when the rendered HTML has the correct lang attribute (e.g., lang="de"). With the UI set to English, the Preview container typically lacks lang="de", so Chromium/Electron picks the wrong dictionary: so hyphenation becomes rare/inconsistent, which hurts readability for long-form notes.

Technical note: browsers choose hyphenation by DOM lang, not CSS. -webkit-locale is unreliable, and CSS cannot set lang.

Proposed solution

Provide a way to set the content language independent of the UI language, and apply it to the Preview content element.

Concretely:

  1. Frontmatter control (preferred)
  • Respect lang: in note frontmatter and set it on the Preview content container (e.g., .markdown-preview-section).
  • Example:
---
lang: de      # or de-CH, en, fr, …
---

Rendered DOM (illustrative):

<div class="markdown-preview-view">
  <div class="markdown-preview-section" lang="de">
    …note content…
  </div>
</div>
  1. Vault default (fallback)
  • A setting like “Default content language for Preview” with options:
    • System/none, Use UI language, or a specific BCP-47 tag (e.g., de-CH).
  • Used when a note doesn’t specify lang in frontmatter.
  1. Nice to have
  • Apply the same logic to the Editor container (CodeMirror) for consistency.
  • Expose a small API so plugins can set/override the content lang for a view.

This is standards-aligned (just setting an attribute), low-risk, and improves typography for many non-English users.

Current workaround (optional)

  • Manually wrap the note body:
<div lang="de">
  …content…
</div>

This immediately fixes Preview hyphenation, but it’s manual, noisy in Markdown, and doesn’t help the Editor.

  • A tiny plugin can force lang="de" on Preview/Editor containers as a stopgap. (I’m happy to share one if useful.)

Related feature requests (optional)

I didn’t find an exact match yet. Suggested keywords others might have used: hyphenation, hyphens auto, preview lang attribute, per-note language, content language.

Maybe these could also help users with this Problem: https://forum.obsidian.md/t/how-to-set-language-for-individual-note-in-order-to-use-proper-spellchecker/31967
This would not only fix hyphenation in Preview, but could also help users who need a proper spellchecker per note. If Obsidian respected a lang: value in frontmatter, the editor could switch the spellchecking dictionary accordingly (e.g., en for English notes, de for German notes).

Environment (for reference):

  • Obsidian version: 1.9.12
  • OS: 15.6.1 (24G90)
  • UI language: English
  • Typical content language: German (de / de-CH)
  • Rendering target: Preview (Editor affected separately)

Thanks for considering! This would let us keep the UI in English while getting correct hyphenation for content written in other languages—crucial for readable, justified long-form notes.