Examine source code of Black Twitch

{
  "manifest_version": 2,
  "name": "Black Twitch",
  "version": "1.1.1",
  "description": "A black theme for Twitch",
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png"
  },
  "permissions": [
    "tabs"
  ],
  "browser_action": {
    "default_icon": {
      "16": "icons/icon-16.png",
      "32": "icons/icon-32.png"
    },
    "default_title": "Black Twitch"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.twitch.tv/*"
      ],
      "run_at": "document_start",
      "css": [
        "css/style.css"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{726799ac-d6e4-4e86-ba87-95943788ed67}"
    }
  }
}