Examine source code of Preussen flag

{
  "name": "Preussen",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "index.jpg"
    },
    "colors": {
      "frame": "rgba(113, 120, 135, 1)",
      "tab_background_text": "rgba(255, 255, 255, 1)",
      "toolbar": "rgba(0, 0, 0, 1)",
      "bookmark_text": "rgba(255, 255, 255, 1)",
      "toolbar_field": "rgba(255, 255, 255, 1)",
      "toolbar_field_text": "rgba(0, 0, 0, 1)",
      "tab_line": "rgba(3, 3, 3, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{bf1bffa8-bcfd-4251-a44a-f5cf93b6980d}"
    }
  }
}