Examine source code of Pinterdark

{
  "manifest_version": 2,
  "name": "Pinterdark",
  "version": "1.0",
  "description": "A simple Firefox extension that allows custom CSS to be injected into Pinterest to allow for an accessible yet modern dark theme on Pinterest domains.",
  "icons": {
    "48": "icons/pinterdark-48_x_48.png",
    "128": "icons/pinterdark-128_x_128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://www.pinterest.com/*"
      ],
      "js": [
        "pinterdark.js"
      ]
    }
  ]
}