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Does not behave as monospaced in GitHub file editor, markdown code blocks etc #379

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Does not behave as monospaced in GitHub file editor, markdown code blocks etc#379

Description

@anentropic
anentropic
opened on Apr 8, 2026

We've all seen wonky ascii diagrams like this and assumed LLMs aren't counting the character columns correctly when generating them:

Image

That's partly true. But when I went to edit the diagram by hand I found that I couldn't make the lines align.

In fact if I navigate the cursor up and down across the lines it takes a zig-zag path!

This is not supposed to happen with a monospaced font!

The issue appears to be the "Monaspace Neon" font that GitHub are using is not behaving as monospaced. After editing the CSS to get an actual monospaced font the chars align in true columns and I was able to edit the diagram into shape. But unfortunately after saving it still renders as per the screenshot at the top - yes, that's the 'fixed' version as rendered in Monaspace Neon.

See this video:

Screen.Recording.2026-04-08.at.17.26.51.mov

Non-fixed-width columns seems like a serious flaw for something supposed to be a monospace font?

Activity

  1. github-project-automation
    added this to Monaspace Planningon Apr 8, 2026

  2. anentropic commented on Apr 14, 2026

    @anentropic
    anentropic
    on Apr 14, 2026
    Author

    Here is the diagram from the video:

    ┌──────────────────────────────────────────────────────────────────┐
│                        BUILD TIME                                │
│                                                                  │
│  ┌─────────────────┐     ┌──────────────────┐     ┌───────────┐  │
│  │ dlt source      │────▶│ dlt-mwaa-build   │────▶│ dag.yaml  │  │
│  │ (Python module) │     │ CLI              │     │           │  │
│  └─────────────────┘     └──────────────────┘     └───────────┘  │
│                                  │                               │
│                                  ▼                               │
│                          ┌──────────────┐                        │
│                          │ Docker image │                        │
│                          │ (ECR)        │                        │
│                          └──────────────┘                        │
└──────────────────────────────────────────────────────────────────┘

  3. heathercran commented on Apr 15, 2026

    @heathercran
    heathercran
    on Apr 15, 2026
    Collaborator

    What program are you seeing this issue in? I've tried pasting the text you supplied into VS Code and I'm not able to recreate the error.

    Image

  4. anentropic commented on Apr 16, 2026

    @anentropic
    anentropic
    on Apr 16, 2026
    Author

    Sorry if it wasn't clear, the issue is in GitHub website - in the file editor for code and also when rendering code-fenced markdown blocks in comments such as the one above, or in README pages etc.

  5. jdunkerley
    added a commit that references this issue on Sep 29, 2026

    Monaspace Neon is the code font, with a Code ligatures setting and a …

    4b7bc1d
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