Examine source code of Yellowstone2

{
  "theme": {
    "images": {
      "theme_frame": "2010June8_YellowstoneUpperCircleDriveFirefoxBorder.jpg"
    },
    "colors": {
      "frame": "#4a4a4a",
      "tab_background_text": "#09173b"
    }
  },
  "version": "2.0",
  "name": "Yellowstone2",
  "manifest_version": 2,
  "description": "Mammoth Springs 2010"
}