Examine source code of Retrospective

{
  "theme": {
    "images": {
      "theme_frame": "retrobwbanner.JPG"
    },
    "colors": {
      "frame": "#d9caca",
      "tab_background_text": "#141212"
    }
  },
  "version": "2.0",
  "name": "Retrospective",
  "manifest_version": 2,
  "description": "cool"
}