Examine source code of Font Changer

{
  "manifest_version": 3,
  "name": "Font Changer",
  "version": "1.2",
  "description": "Change fonts based on selectors.",
  "permissions": [
    "storage",
    "scripting",
    "tabs",
    "activeTab"
  ],
  "action": {
    "default_title": "Font Changer"
  },
  "sidebar_action": {
    "default_panel": "sidepanel.html",
    "default_title": "Font Changer"
  },
  "background": {
    "scripts": [
      "service-worker.js"
    ]
  },
  "host_permissions": [
    "<all_urls>"
  ],
  "web_accessible_resources": [
    {
      "resources": [
        "fonts.json"
      ],
      "matches": [
        "<all_urls>"
      ]
    }
  ],
  "icons": {
    "128": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "fontchanger@instara.app"
    }
  }
}