Examine source code of L4D - Left 4 Dead

{
  "theme": {
    "images": {
      "theme_frame": "l4dtop.jpg"
    },
    "colors": {
      "frame": "#696969",
      "tab_background_text": "#e8e5e5"
    }
  },
  "version": "2.0",
  "name": "L4D - Left 4 Dead",
  "manifest_version": 2,
  "description": "Left 4 Dead 1 characters set in front of a city scape backdrop. I simply put the pieces together."
}