Examine source code of Sketchfox

{
  "theme": {
    "images": {
      "theme_frame": "header4.JPG"
    },
    "colors": {
      "frame": "#000000",
      "tab_background_text": "#000000"
    }
  },
  "version": "2.0",
  "name": "Sketchfox",
  "manifest_version": 2,
  "description": "Ever wonder what Firefox would look like if it were sketched out on a piece of white-lined paper? Well now you can see what it would look like!"
}