Examine source code of Leatherette

{
  "theme": {
    "images": {
      "theme_frame": "Header.jpg"
    },
    "colors": {
      "frame": "#8f8f8f",
      "tab_background_text": "#3b3b3b"
    }
  },
  "version": "2.0",
  "name": "Leatherette",
  "manifest_version": 2,
  "description": "leather-bound firefox"
}