[BUG] Claude desktop on Windows does not correctly render some Greek accents in response.

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

When Claude Desktop (1.3109.0) on Windows (11 Home 25H2) renders Greek, there are certain accents that it can't render correctly - they are offset from the character the accent is supposed to be on:

<img width="574" height="80" alt="Image" src="https://github.com/user-attachments/assets/7e25c536-7c7c-4618-a177-ad28cc73f5c2" />

This was also an issue in Chrome, but a browser extension will allow me to overwrite your font, so I can render:

<img width="497" height="81" alt="Image" src="https://github.com/user-attachments/assets/f3a2155e-d623-494f-bb9b-7e5eff8aa69a" />

Unfortunately, the desktop app doesn't have a good place for me to hook and replace the font.

This problem is Windows specific - Apple does fine.

What Should Happen?

Expected that Claude could render accents above the letters that they correspond to.

Error Messages/Logs

Steps to Reproduce

1. Ask Claude to render the sentence "the shepherd leads the sheep to the water and remains with them" to Koine greek on a Windows desktop instance of Claude.
2. Try to figure out why the accents are rendered over blank spaces rather than the characters they correspond to.

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

1.3109.0

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_