Examine source code of Future Retro

{
  "name": "Retro",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "glittering-flower.png"
    },
    "colors": {
      "frame": "rgba(229, 230, 232, 1)",
      "tab_background_text": "rgba(255, 255, 255, 1)",
      "toolbar": "rgba(34, 87, 19, 0.62)",
      "bookmark_text": "rgba(214, 185, 0, 1)",
      "toolbar_field": "rgba(145, 138, 14, 0.74)",
      "toolbar_field_text": "rgba(0, 0, 0, 1)",
      "tab_line": "rgba(0, 0, 0, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{4a98848f-0805-4ea9-a89d-bd0cd68e4973}"
    }
  }
}