Examine source code of Whimsical Flight

{
  "name": "Whimsical Flight",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "2.jpg"
    },
    "colors": {
      "frame": "rgba(116, 128, 156, 1)",
      "tab_background_text": "rgba(255, 255, 255, 1)",
      "bookmark_text": "rgba(0, 0, 0, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{640f55af-b87a-4c23-b226-f4c7200a1d89}"
    }
  }
}