Examine source code of musescore.com print view

{
  "manifest_version": 2,
  "name": "musescore.com print view",
  "version": "1.0",
  "description": "Simplifies printing of sheet music at musescore.com.",
  "icons": {
    "48": "icons/printview-48.png",
    "96": "icons/printview-96.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.musescore.com/*"
      ],
      "css": [
        "printview.css"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{431099da-166f-4a30-b04c-1d4724e7480c}"
    }
  }
}