Examine source code of ultimate progress bar

{
  "manifest_version": 3,
  "name": "Page Progress Bar",
  "version": "1.0.0",
  "description": "A collapsible per-URL progress bar pinned to the bottom of every page. Adjust with a slider; saves automatically.",
  "permissions": [
    "storage"
  ],
  "action": {
    "default_title": "Toggle progress bar on this page"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "web_accessible_resources": [
    {
      "resources": [
        "pop.mp3"
      ],
      "matches": [
        "<all_urls>"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "page-progress@example.com",
      "strict_min_version": "109.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "content.css"
      ],
      "run_at": "document_idle"
    }
  ]
}