Examine source code of Retromantic

{
  "theme": {
    "images": {
      "theme_frame": "RRheader.jpg"
    },
    "colors": {
      "frame": "#d43f08",
      "tab_background_text": "#ff6666"
    }
  },
  "version": "2.0",
  "name": "Retromantic",
  "manifest_version": 2
}