Examine source code of Cobalt3

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Cobalt",
  "theme": {
    "images": {},
    "properties": {},
    "colors": {
      "toolbar": "rgb(225, 234, 239)",
      "toolbar_text": "rgb(255, 198, 0)",
      "frame": "rgb(25, 53, 73)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(25, 53, 73)",
      "toolbar_field_text": "rgb(234, 238, 255)",
      "tab_line": "rgb(255, 198, 0)",
      "popup": "rgb(25, 53, 73)",
      "popup_text": "rgb(255, 255, 255)",
      "tab_loading": "rgb(255, 198, 0)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{b8fb79e9-8ad7-41d5-bc50-ee26cbf3403c}"
    }
  }
}