Examine source code of Cabernet..

{
  "name": "Cabernet..",
  "manifest_version": 2,
  "version": "3.0",
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "rgba(46, 0, 25, 1)",
      "tab_background_text": "rgba(255, 255, 255, 1)",
      "toolbar": "rgba(48, 0, 25, 0)",
      "bookmark_text": "rgba(255, 255, 255, 1)",
      "toolbar_field": "rgba(48, 0, 25, 0.08)",
      "toolbar_field_text": "rgba(255, 252, 252, 1)",
      "tab_line": "rgba(255, 255, 255, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{fb5b269d-832a-4a5a-ac01-64d21bf43f25}"
    }
  }
}