Examine source code of Minecraft Dark Forest

{
  "name": "Minecraft Dark Forest",
  "manifest_version": 2,
  "version": "3.0",
  "theme": {
    "images": {
      "theme_frame": "Dark Forest.png"
    },
    "colors": {
      "frame": "rgba(229, 230, 232, 1)",
      "tab_background_text": "rgba(207, 207, 207, 1)",
      "toolbar": "rgba(71, 37, 37, 1)",
      "bookmark_text": "rgba(207, 207, 207, 1)",
      "toolbar_field": "rgba(28, 56, 31, 1)",
      "toolbar_field_text": "rgba(207, 207, 207, 1)",
      "tab_line": "rgba(45, 87, 48, 1)"
    }
  }
}