Examine source code of facebook.com

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#8bb5e8",
      "tab_background_text": "#b8dcff"
    }
  },
  "version": "2.0",
  "name": "facebook.com",
  "manifest_version": 2,
  "description": "Facebook persona"
}