Examine source code of Bubble Forest

{
  "theme": {
    "images": {
      "theme_frame": "BF_firefox_skin_header.png"
    },
    "colors": {
      "frame": "#8a8a8a",
      "tab_background_text": "#fafafa"
    }
  },
  "version": "2.0",
  "name": "Bubble Forest",
  "manifest_version": 2,
  "description": "Bubble Forest, the logo I designed."
}