Examine source code of Natural Dark Theme

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Natural Dark Theme",
  "theme": {
    "images": {},
    "properties": {},
    "colors": {
      "toolbar": "rgb(0, 0, 0)",
      "toolbar_text": "rgb(215, 215, 215)",
      "frame": "rgb(0, 0, 0)",
      "tab_background_text": "rgb(180, 180, 180)",
      "toolbar_field": "rgb(20, 20, 20)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(30, 30, 30)",
      "popup": "rgb(30, 30, 30)",
      "popup_text": "rgb(215, 215, 215)",
      "popup_highlight": "rgb(62, 62, 62)",
      "tab_selected": "rgb(30, 30, 30)",
      "tab_loading": "rgb(10, 10, 10)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{408786f6-393c-49f1-af67-06cc0aa4f732}"
    }
  }
}