Examine source code of gfx-playground.net

{
  "theme": {
    "images": {
      "theme_frame": "Header.png"
    },
    "colors": {
      "frame": "#7a7a7a",
      "tab_background_text": "#ffffff"
    }
  },
  "version": "2.0",
  "name": "gfx-playground.net",
  "manifest_version": 2,
  "description": "Visit <a href=\"https://outgoing.prod.mozaws.net/v1/9b8588f5291950ddffdfdced58d597f66a1d0af410d84180815c2682bb5faa61/http%3A//gfx-playground.net\" rel=\"nofollow\">gfx-playground.net</a> for free Graphics and Tutorials..."
}