Examine source code of Vlad test xpi

{
  "description": "Theme using a PNG as the headerURL image, employing a faded edge. See https://developer.mozilla.org/en-US/Add-ons/WebExtensions/Examples#themes",
  "manifest_version": 2,
  "name": "ST theme zip",
  "version": "2.0",
  "homepage_url": "https://github.com/mdn/webextensions-examples/tree/master/themes/weta_fade",
  "theme": {
    "images": {
      "theme_frame": "erbovine.tif"
    },
    "colors": {
      "frame": "#000",
      "tab_background_text": "#000"
    }
  }
}