Examine source code of black on black cubes

{
  "theme": {
    "images": {
      "theme_frame": "header2.JPG"
    },
    "colors": {
      "frame": "#f7f7f7",
      "tab_background_text": "#9c9999"
    }
  },
  "version": "2.0",
  "name": "black on black cubes",
  "manifest_version": 2,
  "description": "easy to look at black and dark gray design"
}