Examine source code of Column Guide Overlay

{
  "manifest_version": 2,
  "name": "Column Guide Overlay",
  "description": "Check a layout against real guides: adjustable columns and gutters, an 8px rhythm grid, and a one-click outline mode that shows every box on the page.",
  "version": "5.3.5",
  "browser_specific_settings": {
    "gecko": {
      "id": "{24ed0e1e-d279-493a-8dde-ddc51e282a2d}",
      "strict_min_version": "101.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "icons": {
    "32": "graphics/icon-32.png",
    "48": "graphics/icon-48.png",
    "64": "graphics/icon-64.png",
    "96": "graphics/icon-96.png",
    "128": "graphics/icon-128.png"
  },
  "browser_action": {
    "default_title": "Column Guide Overlay",
    "default_popup": "popup.html",
    "default_icon": {
      "32": "graphics/icon-32.png",
      "48": "graphics/icon-48.png",
      "64": "graphics/icon-64.png"
    }
  },
  "permissions": [
    "activeTab",
    "storage"
  ]
}