Examine source code of Solo Spades

{
  "theme": {
    "images": {
      "theme_frame": "MozillaSpadesTop4d.jpg"
    },
    "colors": {
      "frame": "#ffffff",
      "tab_background_text": "#000000"
    }
  },
  "version": "2.0",
  "name": "Solo Spades",
  "manifest_version": 2,
  "description": "Spades suit.\nBlue and orange colours represent sky and earth respectively, but also Firefox colours."
}