[BUG] Loading claude-code VSCode extension on firefox 149.0-1 does not load styles correctly

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?

After updating to Firefox 149.0-1 the claude code extension as loded by by browser does not look correct. It was working correctly on firefox version 148.0-1

Browser: Firefox 149.0-1
Environment: code-server (VS Code in browser) (specifically the linuxserver.io ]docker container](https://docs.linuxserver.io/images/docker-code-server/), but any vscode in the browser solution should present same issue)
Claude-code for VS Code plugin version: anthropic.claude-code@2.1.88

Description of the UI breakage
Styles fail to load correctly after updating to firefox 149.0-1. previously loading via firefox 148.0-1 worked successfully as does loading via chrimium based browsers so this seems to be a bug in handleing the firefox browser specifically.

<img width="1047" height="1146" alt="Image" src="https://github.com/user-attachments/assets/13f232a5-57df-41bf-ae1d-e4789faafd5c" />

What Should Happen?

The plugin should load with correct styles just as it did on firefox 148

Error Messages/Logs

Issue appears to be an error fetching the CSS file.

Firefox 149 loads anthropic's css from this URL `https://vscode-remote+code-002eelementia-002elive.vscode-resource.vscode-cdn.net/config/extensions/anthropic.claude-code-2.1.88-linux-x64/webview/index.css` and recieves a network error due to that host not resolving due to NS_ERROR_UNKNOWN_HOST


copy as cUrl for the web request that is failing:

curl 'https://vscode-remote+code-002eelementia-002elive.vscode-resource.vscode-cdn.net/config/extensions/anthropic.claude-code-2.1.88-linux-x64/webview/index.css' \
  -H 'User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:149.0) Gecko/20100101 Firefox/149.0' \
  -H 'Accept: text/css,*/*;q=0.1' \
  -H 'Accept-Language: en-US,en;q=0.9' \
  -H 'Accept-Encoding: gzip, deflate, br, zstd' \
  -H 'Sec-Fetch-Storage-Access: none' \
  -H 'DNT: 1' \
  -H 'Sec-GPC: 1' \
  -H 'Connection: keep-alive' \
  -H 'Sec-Fetch-Dest: style' \
  -H 'Sec-Fetch-Mode: no-cors' \
  -H 'Sec-Fetch-Site: cross-site' \
  -H 'Priority: u=2' \
  -H 'Pragma: no-cache' \
  -H 'Cache-Control: no-cache'


Miliseconds later in my network log i see claude successfully load the javascripts for the extension using this curl formatted query:

curl 'https://vscode-remote+code-002eelementia-002elive.vscode-resource.vscode-cdn.net/config/extensions/anthropic.claude-code-2.1.88-linux-x64/webview/index.js' \
  -H 'User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:149.0) Gecko/20100101 Firefox/149.0' \
  -H 'Accept: */*' \
  -H 'Accept-Language: en-US,en;q=0.9' \
  -H 'Accept-Encoding: gzip, deflate, br, zstd' \
  -H 'Origin: https://code.elementia.live' \
  -H 'DNT: 1' \
  -H 'Sec-GPC: 1' \
  -H 'Sec-Fetch-Dest: script' \
  -H 'Sec-Fetch-Mode: cors' \
  -H 'Sec-Fetch-Site: cross-site' \
  -H 'Connection: keep-alive'

Steps to Reproduce

Steps to reproduce if possible:

Use a web based version of vscode such as code-server, load it and the claude-code plugin via firefox 148 and observe that it works. upgrade to 149 and observe that it now fails to load styles, although functionality appears to be unaffected.

Claude Model

Not sure / Multiple models

Is this a regression?

Yes, this worked in a previous version

Last Working Version

Firefox 148

Claude Code Version

2.1.88

Platform

Anthropic API

Operating System

Other Linux

Terminal/Shell

VS Code integrated terminal

Additional Information

_No response_