Examine source code of Relative Time

{
  "theme": {
    "images": {
      "theme_frame": "time_frame.jpg"
    },
    "colors": {
      "frame": "#5899a1",
      "tab_background_text": "#919191"
    }
  },
  "version": "2.0",
  "name": "Relative Time",
  "manifest_version": 2,
  "description": "Blues, shades, and a lot of clocks...."
}