Examine source code of Transparente Firefox

{
  "theme": {
    "images": {
      "theme_frame": "FirefoxTransparent_Header.png"
    },
    "colors": {
      "frame": "#03132b",
      "tab_background_text": "#dfe0eb"
    }
  },
  "version": "2.0",
  "name": "Transparente Firefox",
  "manifest_version": 2,
  "description": "Transparente Firefox with a little gradient."
}