Examine source code of September Calling

{
  "name": "September Calling",
  "manifest_version": 2,
  "version": "4.0",
  "theme": {
    "images": {
      "theme_frame": "SeptemberCallingHCustom.jpg"
    },
    "colors": {
      "frame": "rgba(117, 101, 30, 1)",
      "tab_background_text": "rgba(255, 252, 240, 1)",
      "toolbar": "rgba(117, 104, 30, 0)",
      "bookmark_text": "rgba(245, 240, 213, 1)",
      "toolbar_field": "rgba(117, 104, 30, 0.06)",
      "toolbar_field_text": "rgba(255, 255, 255, 1)",
      "tab_line": "rgba(255, 255, 255, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{a04b8f34-14df-4e5c-bc82-9cbb897d6525}"
    }
  }
}