Examine source code of River Rocks

{
  "name": "River Rocks",
  "manifest_version": 2,
  "version": "2.0",
  "theme": {
    "images": {
      "theme_frame": "Firefox River Rock Theme.jpg"
    },
    "colors": {
      "frame": "rgba(157, 172, 204, 0.99)",
      "tab_background_text": "rgba(69, 44, 43, 1)",
      "toolbar": "rgba(157, 171, 204, 0)",
      "bookmark_text": "rgba(69, 44, 43, 1)",
      "toolbar_field": "rgba(157, 171, 204, 0.46)",
      "toolbar_field_text": "rgba(69, 44, 43, 1)",
      "tab_line": "rgba(157, 172, 204, 0.99)"
    }
  }
}