Examine source code of High Contrast - Neutral

{
  "manifest_version": 2,
  "version": "3.3",
  "name": "Handsome: Dark",
  "theme": {
    "images": {},
    "properties": {},
    "colors": {
      "toolbar": "rgb(230, 230, 230)",
      "toolbar_text": "rgb(22, 27, 34)",
      "frame": "rgb(22, 27, 34)",
      "tab_background_text": "rgb(230, 230, 230)",
      "toolbar_field": "rgb(255, 255, 255)",
      "toolbar_field_text": "rgb(22, 27, 34)",
      "tab_line": "rgba(22, 27, 34, 0)",
      "popup": "rgb(230, 230, 230)",
      "popup_text": "rgb(22, 27, 34)",
      "tab_loading": "rgba(22, 27, 34, 0)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{8da36bdc-8c81-4d36-b219-84c9ca8ef1a2}"
    }
  }
}