Examine source code of BBC Sounds Dark Mode

{
  "description": "BBC Sounds Dark Mode",
  "manifest_version": 2,
  "name": "BBC Sounds Dark Mode",
  "version": "1.0.1",
  "homepage_url": "https://github.com/Jamie0/BBCSoundsDarkMode",
  "background": {
    "scripts": [
      "bbc-sounds-dark.js"
    ]
  },
  "web_accessible_resources": [
    "dark.css"
  ],
  "permissions": [
    "activeTab",
    "tabs",
    "<all_urls>"
  ]
}