Examine source code of Subtle Grey

{
  "theme": {
    "images": {
      "theme_frame": "ffh.jpg"
    },
    "colors": {
      "frame": "#2b2b2b",
      "tab_background_text": "#454545"
    }
  },
  "version": "2.0",
  "name": "Subtle Grey",
  "manifest_version": 2
}