Examine source code of YLE Comment Collapser

{
  "manifest_version": 3,
  "name": "YLE Comment Collapser",
  "version": "1.1",
  "description": "Your extension's description goes here.",
  "permissions": [
    "activeTab",
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "ylecommentscollapser@parsakaali.com"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "https://yle.fi/*"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "styles.css"
      ]
    }
  ],
  "action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "images/icon16.png",
      "48": "images/icon48.png",
      "128": "images/icon128.png"
    }
  },
  "icons": {
    "16": "images/icon16.png",
    "48": "images/icon48.png",
    "128": "images/icon128.png"
  }
}