Examine source code of Winter Fun

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#f5f6fb",
      "tab_background_text": "#000000"
    }
  },
  "version": "2.0",
  "name": "Winter Fun",
  "manifest_version": 2,
  "description": "Stock credit: <a rel=\"nofollow\" href=\"https://outgoing.prod.mozaws.net/v1/05a1dea074024b97cef6784e09d66ba7b1b33345ea25f201af8566c9a45d6ab7/http%3A//www.freepik.com/vectorpocket\">vectorpocket</a>"
}