Examine source code of SimpleDark

{
  "manifest_version": 2,
  "name": "SimpleDark",
  "permissions": [
    "activeTab",
    "storage",
    "tabs",
    "*://2ch.hk/*"
  ],
  "version": "4.7resigned1",
  "content_scripts": [
    {
      "matches": [
        "*://2ch.hk/*",
        "*://2ch.pm/*",
        "*://2ch.re/*",
        "*://2ch.tf/*",
        "*://2ch.wf/*",
        "*://2ch.yt/*",
        "*://2-ch.so/*"
      ],
      "js": [
        "js/tchsd.js"
      ],
      "run_at": "document_start"
    }
  ],
  "description": "Simple Dark Design for 2ch.hk",
  "icons": {
    "128": "128.png"
  },
  "web_accessible_resources": [
    "css/sd.css",
    "css/nbrd.css",
    "css/nrpt.css",
    "gui/lightning.png",
    "gui/rpt.png",
    "gui/fav.png"
  ],
  "browser_action": {
    "default_title": "SimpleDark",
    "default_icon": "icon.png",
    "default_popup": "popup.html"
  },
  "applications": {
    "gecko": {
      "id": "TwoCH@harkach.mail.ru"
    }
  }
}