Examine source code of Natural 20

{
  "name": "Natural 20",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "Natural 20.png"
    },
    "colors": {
      "frame": "rgba(101, 194, 103, 1)",
      "tab_background_text": "rgba(255, 255, 255, 1)",
      "toolbar": "rgba(102, 196, 107, 0)",
      "bookmark_text": "rgba(252, 181, 114, 1)",
      "toolbar_field": "rgba(102, 196, 107, 0)",
      "toolbar_field_text": "rgba(222, 102, 172, 1)",
      "tab_line": "rgba(255, 255, 255, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{098ff43a-7d13-41ab-a44b-7508a020037e}"
    }
  }
}