Examine source code of Gecko V2

{
  "name": "Gecko V2",
  "manifest_version": 2,
  "version": "2.0",
  "theme": {
    "images": {
      "theme_frame": "Mesa de trabajo 5-100.jpg"
    },
    "colors": {
      "toolbar": "rgba(0, 85, 107, 0.5)",
      "toolbar_field": "rgba(255, 255, 255, 1)",
      "toolbar_field_text": "rgba(0, 85, 107, 1)",
      "frame": "rgba(0, 85, 107, 1)",
      "tab_background_text": "rgba(255, 255, 255, 1)",
      "bookmark_text": "rgba(255, 255, 255, 1)"
    }
  }
}