Examine source code of The Nebula

{
  "theme": {
    "images": {
      "theme_frame": "NebulaHeader.jpg"
    },
    "colors": {
      "frame": "#ff5100",
      "tab_background_text": "#549bff"
    }
  },
  "version": "2.0",
  "name": "The Nebula",
  "manifest_version": 2,
  "description": "Based on the Firefox Nebula Wallpaper.  I take no credit for the design; I just modified it to work as a Persona."
}