Examine source code of Kill em all

{
  "theme": {
    "images": {
      "theme_frame": "PersonaFirefox.jpg"
    },
    "colors": {
      "frame": "#fc0000",
      "tab_background_text": "#423c3c"
    }
  },
  "version": "2.0",
  "name": "Kill em all",
  "manifest_version": 2
}