Examine source code of Join, or Die

{
  "name": "Joinordie",
  "manifest_version": 2,
  "version": "2.0",
  "theme": {
    "images": {
      "theme_frame": "Wewouldbehonouredifyouwouldjoinus.jpg"
    },
    "colors": {
      "frame": "rgba(240, 234, 222, 1)",
      "tab_background_text": "rgba(82, 64, 48, 1)",
      "bookmark_text": "rgba(82, 64, 48, 1)",
      "toolbar_field": "rgba(238, 230, 224, 1)",
      "toolbar_field_text": "rgba(82, 64, 48, 1)"
    }
  }
}