Examine source code of Schulnetz+

{
  "manifest_version": 3,
  "name": "Schulnetz+",
  "description": "Verbesserungen für Schulnetz",
  "version": "0.3.3",
  "browser_specific_settings": {
    "gecko": {
      "id": "schulnetz-plus@sircraft007.local",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "icons": {
    "16": "images/icon-16.png",
    "32": "images/icon-32.png",
    "48": "images/icon-48.png",
    "128": "images/icon-128.png"
  },
  "permissions": [
    "activeTab",
    "tabs",
    "storage"
  ],
  "content_scripts": [
    {
      "js": [
        "content.js"
      ],
      "css": [
        "content.css",
        "current-day-highlighting.css"
      ],
      "matches": [
        "https://www.schulnetz-ag.ch/ksba*"
      ]
    }
  ],
  "action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "images/icon-16.png",
      "32": "images/icon-32.png",
      "48": "images/icon-48.png",
      "128": "images/icon-128.png"
    }
  }
}