Examine source code of Dark Stack

{
  "manifest_version": 2,
  "name": "Dark Stack",
  "version": "1.0",
  "description": "Enables dark mode for all webpages matching stackoverflow.com.",
  "content_scripts": [
    {
      "matches": [
        "*://stackoverflow.com/*"
      ],
      "js": [
        "lights-out.js"
      ]
    }
  ]
}