.oxfmtrc.json:

{
  "$schema": "./node_modules/oxfmt/configuration_schema.json",
  "ignorePatterns": ["pnpm-lock.yaml", "**/routeTree.gen.ts"],
  "semi": false,
  "experimentalTailwindcss": {
    "stylesheet": "./apps/web/src/styles.css",
    "functions": ["classNames"]
  }
}

Running oxfmt:

$ oxfmt .

  × Failed to format file with external formatter: /home/theoludwig/Documents/Fusey/fusey/apps/web/src/styles.css
  │ JS formatFile promise rejected for file: 'styles.css', parser: 'css': GenericFailure, Error: ENOENT: no such file or directory, open '/home/theoludwig/apps/web/src/styles.css'
Error occurred when checking code style in the above files.

So the first path displayed is the correct one. We can try to cat it: cat /home/theoludwig/Documents/Fusey/fusey/apps/web/src/styles.css, and it works no problem, so the path is correct.

However, as we can see it in the output after, it fails, it is trying to get from ../.. apparently.
/home/theoludwig/apps/web/src/styles.css, which this file doesn't exist.

The reproduction is that we need to set experimentalTailwindcss.stylesheet in .oxfmtrc.json.