CSS won't load on Firefox v149 in code-server

Before submitting your bug report

• I've tried using the "Ask AI" feature on the Continue docs site to see if the docs have an answer
• I'm not able to find a related conversation on GitHub discussions that reports the same bug
• I'm not able to find an open issue that reports the same bug
• I've seen the troubleshooting guide on the Continue Docs

Relevant environment info

- OS: Fedora Linux 43
- Continue version: 1.3.38
- IDE version: code-server v4.115.0

Description

I think the default security settings got stricter in Firefox v149 which now breaks CSS loading in Continue if used in a browser IDE (code-server in this case).

The issue seems to be that the index.css file is loaded with Sec-Fetch-Mode: no-cors header that causes it to skip the code-server service worker. That causes an NS_ERROR_UNKNOWN_HOST error, as the domain for the request is not a real one.
The index.js file is loaded with Sec-Fetch-Mode: cors header and works as expected.

I tested on a previous version of Firefox (v148), and in that one the index.css request does go trough the service worker even with Sec-Fetch-Mode: no-cors.

Here is the CSS request in question:

GET /home/codespace/.local/share/code-server/extensions/continue.continue-1.3.38-linux-arm64/gui/assets/index.css undefined
Host: vscode-remote+dev-002dmy-002ddev-002dnext-002djs-002d2bfl-002ecode-002ecanary-002ediploi-002eme.vscode-resource.vscode-cdn.net
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:149.0) Gecko/20100101 Firefox/149.0
Accept: text/css,*/*;q=0.1
Accept-Language: en-GB,en;q=0.9
Accept-Encoding: gzip, deflate, br, zstd
Sec-Fetch-Storage-Access: none
Connection: keep-alive
Referer: https://dev-my-dev-next-js-2bfl.code.canary.diploi.me/
Sec-Fetch-Dest: style
Sec-Fetch-Mode: no-cors
Sec-Fetch-Site: cross-site
DNT: 1
Sec-GPC: 1
Priority: u=2
Pragma: no-cache
Cache-Control: no-cache

And here is the end result:

To reproduce

1. Run code-server and open it in the latest Firefox
2. Install and open the Continue extension

Log output

Start by reproducing the Continue extension in code-server with Firefox 149, then inspect the request for gui/assets/index.css and how it interacts with the code-server service worker. Compare the CSS request with the working index.js request and Firefox 148 behavior; done means the Continue CSS loads without the NS_ERROR_UNKNOWN_HOST failure.