Examine source code of HPDark

{
  "manifest_version": 2,
  "name": "HPDark",
  "version": "0.3",
  "description": "Applies custom made dark mode for HPortal.co.il. Go easy on your eyes!",
  "icons": {
    "16": "icon16.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "content_scripts": [
    {
      "css": [
        "styles.css"
      ],
      "js": [
        "script.js"
      ],
      "matches": [
        "*://hportal.co.il/*"
      ]
    }
  ]
}