Examine source code of Nightshade

{
  "name": "Nightshade",
  "manifest_version": 2,
  "version": "6.0",
  "theme": {
    "images": {
      "theme_frame": "purple-maze-4.png"
    },
    "colors": {
      "frame": "rgba(143, 98, 21, 1)",
      "tab_background_text": "rgba(181, 181, 181, 1)",
      "toolbar": "rgba(0, 0, 0, 0.75)",
      "bookmark_text": "rgba(34, 133, 128, 1)",
      "toolbar_field": "rgba(0, 0, 0, 1)",
      "toolbar_field_text": "rgba(85, 171, 115, 1)",
      "tab_line": "rgba(89, 67, 68, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{56fcd9e6-5eba-4fc3-a7c4-1f2634a925c9}"
    }
  }
}