Examine source code of Swallowtail

{
  "theme": {
    "images": {
      "theme_frame": "swallowtailpersona.jpg"
    },
    "colors": {
      "frame": "#6b6969",
      "tab_background_text": "#030303"
    }
  },
  "version": "2.0",
  "name": "Swallowtail",
  "manifest_version": 2,
  "description": "European Swallowtail Butterfly"
}