Examine source code of Justbase.fm 2

{
  "theme": {
    "images": {
      "theme_frame": "Justbaseheadder.jpg"
    },
    "colors": {
      "frame": "#b52222",
      "tab_background_text": "#b52222"
    }
  },
  "version": "2.0",
  "name": "Justbase.fm 2",
  "manifest_version": 2,
  "description": "2 Justbase Firefox Design"
}