Examine source code of Cool Blue/Dark backround

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Windows Cool Blue/Dark backround",
  "theme": {
    "images": {},
    "properties": {},
    "colors": {
      "toolbar": "rgb(41, 42, 44)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(45, 125, 152)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(0, 0, 0)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(0, 0, 0)",
      "popup": "rgb(41, 42, 44)",
      "popup_text": "rgb(255, 255, 255)",
      "tab_loading": "rgb(0, 0, 0)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{3bbc8dab-811c-43fa-a014-33adcca6de01}"
    }
  }
}