Examine source code of Blockheads

{
  "theme": {
    "images": {
      "theme_frame": "blockheads.png"
    },
    "colors": {
      "frame": "#3667b5",
      "tab_background_text": "#000033"
    }
  },
  "version": "2.0",
  "name": "Blockheads",
  "manifest_version": 2,
  "description": "Simple design intended to provided a non-intrusive Persona."
}