Examine source code of Startpage Tweaks

{
  "manifest_version": 3,
  "name": "Startpage Tweaks",
  "version": "1.0.0",
  "description": "Make Startpage more awesome.",
  "icons": {
    "48": "icons/icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "startpage-tweaks@cyb3rko.de"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "https://*.startpage.com/sp/search*",
        "https://*.startpage.com/do/search*",
        "https://*.startpage.com/do/dsearch*"
      ],
      "js": [
        "enhance.js"
      ]
    }
  ]
}