Examine source code of niji no uta

{
  "theme": {
    "images": {
      "theme_frame": "-1.jpg"
    },
    "colors": {
      "frame": "#949494",
      "tab_background_text": "#4a4a4a"
    }
  },
  "version": "2.0",
  "name": "niji no uta",
  "manifest_version": 2,
  "description": "244"
}