Make Markdown preview paragraph line-height configurable (currently hardcoded to 1.3, too tight for CJK)

[suin]

Motivation

The Markdown preview uses a hardcoded paragraph line-height of rems(1.3). For Latin scripts this is acceptable, but for CJK text (Japanese, Chinese, Korean) it makes paragraphs feel cramped and noticeably hurts readability. Latin glyphs use only part of the em-box and have ascenders/descenders that create visual breathing room; CJK glyphs fill the em-box with flat tops/bottoms, so the same multiplier collapses the space between baselines.

For comparison, GitHub's Markdown rendering uses 1.5 for paragraphs, and typographic guidelines for body CJK text typically recommend 1.7–2.0.

Current behavior

• The preview's paragraph element unconditionally applies line_height(rems(1.3)) in crates/markdown/src/markdown.rs around L1164–1165.
• MarkdownStyle::default() sets height_is_multiple_of_line_height: false, and the MarkdownFont::Preview branch does not flip it. The hardcoded path is always taken in the preview.
• buffer_line_height from ThemeSettings is consumed only in crates/markdown_preview/src/markdown_preview_view.rs::line_scroll_amount — it controls scrolling, not rendering.
• As a result, no setting today (global buffer_line_height, languages.Markdown.buffer_line_height, or the new markdown_preview_theme from markdown_preview: Independent font family and theme #54003) changes the preview's paragraph spacing.

Workarounds today

Increasing buffer_font_size widens the gap as a side effect (gap = font_size × 1.3), but text size grows in lockstep. There is no other knob.

Proposal

In rough order of scope:

1. Bump the constant — change rems(1.3) to rems(1.5) to match GitHub. Improves CJK readability immediately, no new setting.
2. Add markdown_preview_line_height — parallel to markdown_preview_theme and markdown_preview_font_family (markdown_preview: Independent font family and theme #54003), accepting the same shape as buffer_line_height: "standard" | "comfortable" | { "custom": <number> }. Default unchanged. Preview-only, leaves code editing untouched.
3. Reuse buffer_line_height — flip height_is_multiple_of_line_height to true for the preview path so the existing setting applies. Simpler, but couples preview prose readability to code editor line-height.

Option 2 follows the precedent set by #54003 and keeps preview tuning independent from code.

Related

• markdown_preview: Independent font family and theme #54003 (merged) — added markdown_preview_theme and markdown_preview_font_family.
• Discussion Better Markdown preview style. #54251 — broader request to improve preview spacing, no CJK focus.
• markdown_preview: Add font size settings and actions #55489 / cmd-= / cmd-- doesn't zoom Markdown preview body text (only buffer_font_size, not ui_font_size) #55374 — zoom shortcuts for preview body.
• Unrendered boxes in markdown preview of italic CJK characters #33952 — italic CJK rendering (separate bug).

Environment

Zed: 1.1.6+stable.265 (96962914296a22c22a7f226b5ae7de4dd0e34729)
OS: macOS 24.6.0

[aita-you-dont-c]

Need for english too.

[Dolyfin]

The current value for latin (English) is also by far too tight. Not being dyslexic but paragraphs of text is simply easier to read from the editor than the current viewer. 1.5 should be the default value and configurable as well if anyone cares to have it more compact or more readable for CJK languages.

[alexvcasillas]

I think this configuration is very much needed across the board

[kolyasya]

Please add some basic configuration for markdown preview

[ricardobeat]

+1. Current Markdown preview styling is not great:

[adampatterson]

I'm old, I need this 😂