Examine source code of FMINSIDE Stats Modifier

{
  "manifest_version": 2,
  "name": "FMINSIDE Stats Modifier",
  "version": "1.2",
  "description": "Modifies the attributes on the FMINSIDE webpage to display stats in the 1-20 range",
  "permissions": [
    "activeTab"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://fminside.net/*"
      ],
      "js": [
        "contentScript.js"
      ],
      "run_at": "document_end"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{00121053-a8de-4f0f-93c6-64fa7c9cb49b}"
    }
  }
}