Examine source code of Windows 8 shadow

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#ffffff",
      "tab_background_text": "#000000"
    }
  },
  "version": "2.0",
  "name": "Windows 8 shadow",
  "manifest_version": 2,
  "description": "Theme designed to fit in with Windows 8, adds a soft shadow behind the tabs and other GUI elements."
}