Examine source code of MacOS Dark

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "MacOS Dark",
  "theme": {
    "images": {},
    "properties": {},
    "colors": {
      "toolbar": "rgb(58, 58, 60)",
      "toolbar_text": "rgb(223, 223, 225)",
      "frame": "rgb(28, 28, 30)",
      "tab_background_text": "rgb(223, 223, 225)",
      "toolbar_field": "rgb(44, 44, 46)",
      "toolbar_field_text": "rgb(223, 223, 225)",
      "tab_line": "rgb(58, 58, 60)",
      "popup": "rgb(58, 58, 60)",
      "popup_text": "rgb(223, 223, 225)",
      "tab_loading": "rgb(58, 58, 60)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{33bdf01a-77c8-48c5-a021-616c7506dba4}"
    }
  }
}