Examine source code of Reddit Auto Dark Mode

{
  "name": "Reddit Auto Dark Mode",
  "description": "Make reddit respect system theme",
  "version": "1.0.2",
  "manifest_version": 3,
  "content_scripts": [
    {
      "matches": [
        "https://new.reddit.com/*"
      ],
      "js": [
        "darkMode.js"
      ]
    }
  ],
  "icons": {
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "usfrasufgi@avuibaerviub.com"
    }
  }
}