Examine source code of Chromium Dark

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "FFDark",
  "theme": {
    "images": {},
    "properties": {},
    "colors": {
      "toolbar": "rgb(48, 52, 67)",
      "toolbar_text": "rgb(228, 230, 233)",
      "frame": "rgb(12, 12, 23)",
      "tab_background_text": "rgb(228, 230, 233)",
      "toolbar_field": "rgb(12, 12, 23)",
      "toolbar_field_text": "rgb(228, 230, 233)",
      "tab_line": "rgb(48, 52, 67)",
      "popup": "rgb(48, 52, 67)",
      "popup_text": "rgb(228, 230, 233)",
      "tab_loading": "rgb(48, 52, 67)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{f9c97c55-f8c4-493a-9f6f-4c3e53d56005}"
    }
  }
}