Examine source code of Subtle Dark

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Subtle Dark",
  "theme": {
    "images": {},
    "properties": {},
    "colors": {
      "toolbar": "rgb(36, 41, 50)",
      "toolbar_text": "rgb(221, 221, 221)",
      "frame": "rgb(36, 41, 50)",
      "tab_background_text": "rgb(189, 191, 193)",
      "toolbar_field": "rgb(39, 43, 51)",
      "toolbar_field_text": "rgb(196, 197, 199)",
      "tab_line": "rgb(69, 73, 81)",
      "popup": "rgb(51, 58, 71)",
      "popup_text": "rgb(201, 202, 206)",
      "tab_loading": "rgb(69, 73, 81)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{37ed2162-7ff6-4c49-973c-516fef5bf89e}"
    }
  }
}