Examine source code of Steam-hider

{
  "manifest_version": 2,
  "name": "Steam-hider",
  "description": "Hides the lobby invite link from Geoguessr",
  "version": "0.0.1",
  "author": "Fabian Hofstätter",
  "icons": {
    "48": "./img/icon.png"
  },
  "permissions": [
    "scripting"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://www.geoguessr.com/*"
      ],
      "css": [
        "css/general.css"
      ],
      "run_at": "document_start"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{47dd358f-ed75-45ce-a593-436e1819175c}"
    }
  }
}