Examine source code of Win 8.1 Blue

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#61c2ff",
      "tab_background_text": "#61c2ff"
    }
  },
  "version": "2.0",
  "name": "Win 8.1 Blue",
  "manifest_version": 2,
  "description": "This theme is regularly use for firefox in windows 8. But if your using a theme with Win7 of Win8 then you might want to get this."
}