Examine source code of CSSViewer

{
  "name": "CSSViewer",
  "manifest_version": 2,
  "version": "1.2resigned1",
  "description": "A simple CSS property viewer. For Firefox Quantum",
  "icons": {
    "16": "img/16.png",
    "22": "img/22.png",
    "24": "img/24.png",
    "32": "img/32.png",
    "48": "img/48.png"
  },
  "options_ui": {
    "page": "option.html",
    "browser_style": true
  },
  "background": {
    "page": "background.html"
  },
  "browser_action": {
    "default_icon": "img/16.png",
    "default_title": "CSSViewer"
  },
  "web_accessible_resources": [
    "img/header.png",
    "img/body.png",
    "img/list.png",
    "img/footer.png",
    "img/bullet.png"
  ],
  "permissions": [
    "tabs",
    "http://*/*",
    "https://*/*",
    "file://*/*",
    "contextMenus"
  ],
  "applications": {
    "gecko": {
      "id": "CSSViewer@quantum"
    }
  }
}