Examine source code of MmMm...Doughnuts

{
  "theme": {
    "images": {
      "theme_frame": "dougnut-header2.JPG"
    },
    "colors": {
      "frame": "#f2d918",
      "tab_background_text": "#522b08"
    }
  },
  "version": "2.0",
  "name": "MmMm...Doughnuts",
  "manifest_version": 2,
  "description": "Homer Simpson theme, Lots of cute cartoon doughnuts, on a coffee coloured backdrop."
}