Examine source code of space cage

{
  "theme": {
    "images": {
      "theme_frame": "ffoxheader2.jpg"
    },
    "colors": {
      "frame": "#9e9e9e",
      "tab_background_text": "#acf7e9"
    }
  },
  "version": "2.0",
  "name": "space cage",
  "manifest_version": 2
}