Examine source code of sphynx-cat

{
  "theme": {
    "images": {
      "theme_frame": "dibuix3.jpg"
    },
    "colors": {
      "frame": "rgba(229,230,232,1)",
      "tab_background_text": "#e8f0ef"
    }
  },
  "version": "2.0",
  "name": "sphynx-cat",
  "manifest_version": 2,
  "description": "<a href=\"https://outgoing.prod.mozaws.net/v1/3ca4dbfa63cdabc8e3238f2478dbc66e2acd977fbad41cbc688418f8bf900d06/http%3A//www.sphynx-cat.es\" rel=\"nofollow\">www.sphynx-cat.es</a>"
}