Examine source code of Dark Scroll

{
  "name": "Dark Scroll",
  "short_name": "Dark Scroll",
  "description": "Makes the scrollbars dark in Firefox. This should be done by each site some day, not by an addon :(",
  "version": "2.0.0",
  "manifest_version": 2,
  "icons": {
    "16": "images/icon-16.png",
    "19": "images/icon-19.png",
    "38": "images/icon-38.png",
    "48": "images/icon-48.png",
    "96": "images/icon-96.png",
    "128": "images/icon-128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "css": [
        "dark_scroll_bars.css"
      ]
    }
  ],
  "permissions": [
    "activeTab"
  ]
}