Examine source code of RoughGlass

{
  "theme": {
    "images": {
      "theme_frame": "firefox-persona-01-Lasi_header-06.jpg"
    },
    "colors": {
      "frame": "#7a784d",
      "tab_background_text": "#fff1b2"
    }
  },
  "version": "2.0",
  "name": "RoughGlass",
  "manifest_version": 2,
  "description": "abstract photo of a grainy window glass"
}