Examine source code of Midnight Themes

{
  "manifest_version": 2,
  "name": "Midnight",
  "version": "2.0",
  "description": "A set of themes for Wattpad.",
  "icons": {
    "16": "icon16.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "browser_action": {
    "default_icon": {
      "16": "icon16.png",
      "48": "icon48.png"
    },
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.wattpad.com/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_start",
      "all_frames": true
    }
  ],
  "web_accessible_resources": [
    "themes/*.css"
  ],
  "permissions": [
    "storage"
  ],
  "applications": {
    "gecko": {
      "id": "midnightthemes@athena.com"
    }
  }
}