Examine source code of Roundless

{
  "manifest_version": 2,
  "name": "Roundless",
  "version": "1.0",
  "description": "Remove all round borders from every website.",
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "css": [
        "roundless.css"
      ],
      "run_at": "document_start"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{1fc9ad97-411c-4748-9d11-bafd48a9de53}"
    }
  }
}