Examine source code of NcOnlyDarkMode

{
  "description": "Hi",
  "manifest_version": 2,
  "name": "DarkMode",
  "version": "0.0.1b",
  "icons": {
    "48": "icon48.png",
    "96": "icon96.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://contenthub.netacad.com/*"
      ],
      "js": [
        "script.js"
      ]
    }
  ]
}