Examine source code of We love Firefox

{
  "theme": {
    "images": {
      "theme_frame": "firefox.jpg"
    },
    "colors": {
      "frame": "rgba(229,230,232,1)",
      "tab_background_text": "#ffffff"
    }
  },
  "version": "2.0",
  "name": "We love Firefox",
  "manifest_version": 2,
  "description": "Mozilla Firefox vs. Internet Explorer: If Firefox met the Internet Explorer, Firefox would eat it. Cause we love Firefox!"
}