Examine source code of Janguru (Niivu)

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Janguru",
  "theme": {
    "images": {},
    "properties": {},
    "colors": {
      "toolbar": "rgb(23, 23, 23)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(23, 23, 23)",
      "tab_background_text": "rgb(151, 151, 151)",
      "toolbar_field": "rgb(23, 23, 23)",
      "toolbar_field_text": "rgb(151, 151, 151)",
      "tab_line": "rgb(23, 23, 23)",
      "popup": "rgb(23, 23, 23)",
      "popup_text": "rgb(151, 151, 151)",
      "popup_border": "rgb(23, 23, 23)",
      "sidebar_border": "rgb(23, 23, 23)",
      "sidebar_highlight": "rgb(62, 62, 62)",
      "sidebar": "rgb(23, 23, 23)",
      "tab_selected": "rgb(45, 45, 45)",
      "toolbar_bottom_separator": "rgb(23, 23, 23)",
      "toolbar_field_border_focus": "rgb(23, 23, 23)",
      "toolbar_field_highlight_text": "rgb(255, 255, 255)",
      "toolbar_field_highlight": "rgb(119, 119, 119)",
      "toolbar_field_text_focus": "rgb(151, 151, 151)",
      "toolbar_top_separator": "rgb(23, 23, 23)",
      "tab_loading": "rgb(23, 23, 23)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{1a2bc1c0-3edc-47b6-acd8-964921c75762}"
    }
  }
}