Examine source code of Otto Numbers

{
  "name": "Otto Numbers",
  "version": "1.0.1",
  "manifest_version": 2,
  "browser_specific_settings": {
    "gecko": {
      "id": "personalxtdie@gmail.com",
      "strict_min_version": "42.0"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "https://*.twitch.tv/*"
      ],
      "css": [
        "styles.css"
      ],
      "js": [
        "script.js"
      ]
    }
  ]
}