Examine source code of Jambofy

{
  "manifest_version": 3,
  "name": "Jambofy",
  "version": "0.1.2",
  "description": "Improves boring youtube thumbnails and Jambofys them",
  "host_permissions": [
    "https://www.youtube.com/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "jambofy@jambi",
      "strict_min_version": "48.0"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.youtube.com/*"
      ],
      "js": [
        "main.js"
      ]
    }
  ],
  "web_accessible_resources": [
    {
      "resources": [
        "assets/images/*.png"
      ],
      "matches": [
        "*://*/*"
      ]
    }
  ],
  "action": {
    "default_icon": {
      "16": "assets/icons/icon-16.png",
      "24": "assets/icons/icon-24.png",
      "32": "assets/icons/icon-32.png",
      "128": "assets/icons/icon-128.png"
    },
    "default_title": "Jambofyer"
  },
  "icons": {
    "16": "assets/icons/icon-16.png",
    "24": "assets/icons/icon-24.png",
    "32": "assets/icons/icon-32.png",
    "128": "assets/icons/icon-128.png"
  }
}