Examine source code of The 4th sky

{
  "theme": {
    "images": {
      "theme_frame": "sky4.jpg"
    },
    "colors": {
      "frame": "#414141",
      "tab_background_text": "#737373"
    }
  },
  "version": "2.0",
  "name": "The 4th sky",
  "manifest_version": 2,
  "description": "Feel the dark"
}