Examine source code of Red Red Hearts

{
  "theme": {
    "images": {
      "theme_frame": "DrawingRedHearts.jpg"
    },
    "colors": {
      "frame": "#732c8f",
      "tab_background_text": "#3d2691"
    }
  },
  "version": "2.0",
  "name": "Red Red Hearts",
  "manifest_version": 2,
  "description": "Loving Hearts"
}