Examine source code of mdm

{
  "description": "minimalist dark mode",
  "manifest_version": 2,
  "name": "mdm",
  "version": "1.0.0.2",
  "icons": {
    "48": "icons/border-48.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "mdm.js"
      ]
    }
  ]
}