Examine source code of Fox in Dark

{
  "theme": {
    "images": {
      "theme_frame": "header.jpg"
    },
    "colors": {
      "frame": "#111629",
      "tab_background_text": "#f4f4f7"
    }
  },
  "version": "2.0",
  "name": "Fox in Dark",
  "manifest_version": 2,
  "description": "Blue is color of earth... Its Firefox enjoying his new era in dark night "
}