Examine source code of Nerdiness

{
  "theme": {
    "images": {
      "theme_frame": "nerdiness6.jpg"
    },
    "colors": {
      "frame": "#c2c0c0",
      "tab_background_text": "#d9b827"
    }
  },
  "version": "2.0",
  "name": "Nerdiness",
  "manifest_version": 2,
  "description": "If you're a nerd, this could very well be the persona for your computer!"
}