Examine source code of flat_grey

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "classic",
  "theme": {
    "images": {},
    "properties": {},
    "colors": {
      "toolbar": "rgb(219, 220, 219)",
      "toolbar_text": "rgb(136, 141, 129)",
      "frame": "rgb(201, 197, 197)",
      "tab_background_text": "rgb(41, 102, 245)",
      "toolbar_field": "rgba(255, 255, 255, 0.7)",
      "toolbar_field_text": "rgb(67, 81, 168)",
      "tab_line": "rgb(41, 80, 245)",
      "popup": "rgb(219, 220, 219)",
      "popup_text": "rgb(33, 64, 120)",
      "toolbar_bottom_separator": "rgb(232, 231, 234)",
      "toolbar_top_separator": "rgb(203, 202, 204)",
      "tab_loading": "rgb(41, 80, 245)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{d30ac2b6-d9d1-4da3-b7cd-4458ee4d7eda}"
    }
  }
}