Examine source code of Smooth Dark Gradient

{
  "name": "Smooth Dark Gradient",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "frame.png"
    },
    "colors": {
      "frame": "#000F",
      "ntp_background": "#1B1B1B",
      "popup": "#222",
      "tab_background_text": "rgba(255, 255, 255, 1)",
      "toolbar": "#AAA2",
      "toolbar_bottom_separator": "rgba(255, 255, 255, 0.3)",
      "toolbar_top_separator": "rgba(255, 255, 255, 0.3)",
      "toolbar_field_border": "rgba(255, 255, 255, 0.3)",
      "bookmark_text": "rgba(255, 255, 255, 1)",
      "toolbar_field": "#222A",
      "toolbar_field_text": "rgba(255, 255, 255, 1)",
      "tab_line": "rgba(255, 255, 255, 0.3)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{fd7e3685-876c-42dc-8d09-ae5e41088b0f}"
    }
  }
}