Examine source code of Smooth Dark Grey Gradient

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Smooth Dark Grey Gradient",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "center top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(57, 57, 57)",
      "toolbar_text": "rgb(221, 221, 221)",
      "frame": "rgb(32, 32, 32)",
      "tab_background_text": "rgb(215, 215, 215)",
      "toolbar_field": "rgb(32, 32, 32)",
      "toolbar_field_text": "rgb(221, 221, 221)",
      "tab_line": "rgb(64, 64, 64)",
      "popup": "rgb(41, 41, 41)",
      "popup_text": "rgb(215, 215, 215)",
      "ntp_background": "rgb(16, 16, 16)",
      "popup_border": "rgb(64, 64, 64)",
      "popup_highlight": "rgb(64, 64, 64)",
      "sidebar_border": "rgb(16, 16, 16)",
      "sidebar": "rgb(32, 32, 32)",
      "toolbar_field_border_focus": "rgb(64, 64, 64)",
      "toolbar_field_border": "rgb(64, 64, 64)",
      "toolbar_field_focus": "rgba(16, 16, 16, 0.7)",
      "toolbar_top_separator": "rgb(64, 64, 64)",
      "tab_loading": "rgb(64, 64, 64)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{1f2933ab-fc14-4035-9a4b-75346e25736a}"
    }
  }
}