[BUG] Preview panel renders blank / light-mode-on-dark-background for HTML files in Desktop app

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?

Preview panel in the desktop app (not terminal) shows blank box for HTML files; briefly flashed garbled preview with light-mode text on dark background (black text on dark gray)

What Should Happen?

The preview panel should show the rendered html file in a readable format.

Error Messages/Logs

Steps to Reproduce

Have Claude generate an HTML file → observe side preview panel

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

Claude for Mac Version 1.7196.0 (2dbd78)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

<img width="1214" height="915" alt="Image" src="https://github.com/user-attachments/assets/0f0ae2bc-e78a-494d-97ab-bc7795484c1d" />