Examine source code of Dark Vortex

{
  "theme": {
    "images": {
      "theme_frame": "firefoxcustombrowserthemetopbar.png"
    },
    "colors": {
      "frame": "#4f4f4f",
      "tab_background_text": "#000000"
    }
  },
  "version": "2.0",
  "name": "Dark Vortex",
  "manifest_version": 2,
  "description": "Dark, and perfectly senseless persona theme. Just wanted to take a whack at it."
}