Examine source code of N4K

{
  "name": "N4K",
  "manifest_version": 2,
  "version": "3.0",
  "theme": {
    "images": {
      "theme_frame": "ff.jpg"
    },
    "colors": {
      "frame": "rgba(27, 31, 35, 1)",
      "tab_background_text": "rgba(106, 115, 125, 1)",
      "toolbar": "rgba(36, 41, 46, 1)",
      "bookmark_text": "rgba(225, 228, 232, 1)",
      "toolbar_field": "rgba(27, 31, 35, 1)",
      "toolbar_field_text": "rgba(111, 66, 193, 1)",
      "tab_line": "rgba(36, 41, 46, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{0ebba481-c674-43e2-a7c6-d8dc9010161c}"
    }
  }
}