Examine source code of Silverbeam

{
  "theme": {
    "images": {
      "theme_frame": "starry_castle_sky_persona.jpg"
    },
    "colors": {
      "frame": "#7b4180",
      "tab_background_text": "#fcfcfc"
    }
  },
  "version": "2.0",
  "name": "Silverbeam",
  "manifest_version": 2,
  "description": "Mystical Starry night sky with Castle. A fairytale of wonder. See my gallery at www.silverbeam.deviantart.com"
}