[BUG] Planning window code blocks unreadable on light VSCode themes (white text on light gray)

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?

In the plan approval window, code blocks render with white (or near-white) text on a light gray background, making them completely unreadable when using a light VSCode color theme.

<img width="722" height="531" alt="Image" src="https://github.com/user-attachments/assets/11cbff01-5058-4be8-a1f5-9bef32b90c7d" />

Environment:
Claude Code VSCode extension
Platform: Linux
VSCode theme: Default High Contrast Light

What Should Happen?

Code blocks should adapt to the active VSCode theme, using dark text on a light background (or respecting --vscode-* CSS variables for contrast).

Error Messages/Logs

Steps to Reproduce

The webview should use VSCode's built-in CSS variables

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

v2.1.162

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

VS Code integrated terminal

Additional Information

_No response_