Examine source code of Clockwork1

{
  "theme": {
    "images": {
      "theme_frame": "cw_ff_header.png"
    },
    "colors": {
      "frame": "rgba(229,230,232,1)",
      "tab_background_text": "#000000"
    }
  },
  "version": "2.0",
  "name": "Clockwork1",
  "manifest_version": 2,
  "description": "<a href=\"https://outgoing.prod.mozaws.net/v1/944d38a246a5b0a03047137956c50208f6dafb92d616b33d21681afede180580/http%3A//www.clockwork.net\" rel=\"nofollow\">www.clockwork.net</a>"
}