Examine source code of Dark

{
  "name": "Dark",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "Untitled.png"
    },
    "colors": {
      "frame": "rgba(15, 15, 15, 1)",
      "tab_background_text": "rgba(255, 255, 255, 1)",
      "toolbar": "rgba(41, 41, 41, 1)",
      "bookmark_text": "rgba(191, 191, 191, 1)",
      "toolbar_field": "rgba(74, 74, 74, 1)",
      "toolbar_field_text": "rgba(173, 173, 173, 1)",
      "tab_line": "rgba(71, 76, 112, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{64f96c27-e484-4062-a257-99a4897e6315}"
    }
  }
}