Examine source code of Breakpoint Viewer

{
  "manifest_version": 2,
  "name": "Breakpoint Viewer",
  "description": "See which CSS breakpoint is active on any website. Supports Tailwind, Bootstrap, and custom presets.",
  "version": "1.0.7",
  "icons": {
    "16": "icon16.png",
    "32": "icon32.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "permissions": [
    "activeTab",
    "scripting",
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      },
      "id": "{9156a5eb-1de4-473c-88c0-b7fb0447f2c1}"
    }
  },
  "browser_action": {
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "http://*/*",
        "https://*/*"
      ],
      "run_at": "document_idle",
      "js": [
        "content-scripts/content.js"
      ]
    }
  ]
}