Examine source code of Spring Bird

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#d1ceaa",
      "tab_background_text": "#000000"
    }
  },
  "version": "2.0",
  "name": "Spring Bird",
  "manifest_version": 2,
  "description": "Stock credit: <a rel=\"nofollow\" href=\"https://outgoing.prod.mozaws.net/v1/296d7a8a7706589c4967341948c5eb6bd07bce4c39dce1a79b6671c91f36374c/https%3A//pixabay.com/en/users/jill111-334088/\">Jill Wellington\n</a>"
}