Examine source code of sigma1234

{
  "name": "sigma",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "Amoledbackgrounds-ju6dyv.jpg"
    },
    "colors": {
      "frame": "rgba(0, 0, 0, 1)",
      "tab_background_text": "rgba(250, 250, 250, 1)",
      "toolbar": "rgba(0, 0, 0, 1)",
      "bookmark_text": "rgba(255, 255, 255, 1)",
      "toolbar_field": "rgba(0, 0, 0, 1)",
      "tab_line": "rgba(0, 0, 0, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{28002aae-3e2b-4570-9f6d-2154b69c3dad}"
    }
  }
}