Examine source code of Kali

{
  "name": "Kali",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "kali-actiniaria-16x9.png"
    },
    "colors": {
      "frame": "rgba(32, 32, 32, 1)",
      "tab_background_text": "rgba(209, 209, 209, 1)",
      "toolbar": "rgba(66, 66, 66, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{3f868844-fde8-4657-b24e-6e3bdff3682a}"
    }
  }
}