Examine source code of Style Info

{
  "manifest_version": 2,
  "name": "Style Info",
  "version": "1.0.3",
  "description": "Detect style on element hover",
  "author": "Bozidar Atanasovski",
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "/scripts/page.js"
      ],
      "css": [
        "/styles/page.css"
      ]
    }
  ],
  "background": {
    "scripts": [
      "/scripts/background.js"
    ]
  },
  "browser_action": {
    "default_icon": {
      "48": "/icons/icon.png"
    },
    "default_title": "Style info"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{1c6ff34d-c3a0-43df-b711-109e4d588c7d}"
    }
  }
}