Possible bug on Windows 25H2

[avivkeller]

May I ask for some browser + extension information, we've received a similar report before, but, like this one, I can't reproduce, unfortunately:

I'm seeing the issue only on Windows 11 25H2, not on Ubuntu 24.04.4 LTS:

• Google Chrome Version 150.0.7871.125 (Official Build) (64-bit) - also in Incognito mode
• Mozilla Firefox 152.0.6 (64-bit) - also in private window

Originally posted by @MikeMcC399 in nodejs/node#62045 (comment)

[MikeMcC399]

The table in https://nodejs-api-docs-tooling.vercel.app/url.html#url-strings-and-url-objects is misaligned

Compare to https://nodejs.org/api/url.html#url-strings-and-url-objects

[bmuenzenmeyer]

Also seeing it on Windows 10 22H2
Chrome Version 150.0.7871.101 (Official Build) (64-bit)

[bmuenzenmeyer]

Perfect use case for Claude Opus. I let it read this issue while I made dinner.
What to do to replace the font-stack carefully across platforms is next.

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Root cause (verified on this Windows machine)
The table is pure Unicode Box Drawing glyphs (│ ┌ ─ ┼ ┬ ┴ ┤ ├, U+2500–U+257F). Alignment requires every glyph to share one advance width.

IBM Plex Mono contains no Box Drawing glyphs. So the browser draws the letters in IBM Plex Mono but substitutes a different font for the box characters only. On Windows that substitute is Consolas:

IBM Plex Mono letter advance @ 16px = 9.609px (0.60em)
Substituted box-glyph advance (Consolas) = 8.797px (0.55em)
That 0.8px-per-character gap accumulates across the ~98-char-wide diagram and shears every vertical rule out of line — exactly the screenshot.

Two facts that nail it:

Why it's Windows-only: on Linux/Mac the box-glyph substitute happens to match Plex's width; on Windows (Consolas) it doesn't.
Why nodejs.org is fine on the same machine: its code stack is SFMono-Regular, Menlo, Consolas, …, monospace. With no SF Mono/Menlo on Windows it resolves to Consolas for everything — and Consolas does include box-drawing glyphs, so letters and box chars are one font, uniformly 7.13px, perfectly aligned.
The cruel irony: doc-kit's diagram breaks because IBM Plex Mono loads successfully. If it failed, everything would fall to Consolas and line up.

The fix constraint
Google Fonts only serves latin/cyrillic/greek subsets — the Box Drawing block (U+2500) is in none of them, so no Google-hosted font will ever supply these glyphs. They always fall back to a local font. Alignment therefore requires letters and box chars to come from one font of matching width. Options:

A — Drop IBM Plex Mono for these blocks (use the system monospace stack like nodejs.org / the legacy generator). Zero new assets; text+box both render in Consolas → aligned. Proven on this machine (my control showed monospace = 8.797px for both letter and box). Cost: text diagram blocks (and possibly all code) lose Plex branding.
B — Self-host a webfont that includes Box Drawing at Plex's 0.60em advance, scoped via @font-face { unicode-range: U+2500-257F }, keeping IBM Plex Mono for text. Keeps branding; costs a bundled woff2.