Examine source code of Dark Gray and Green

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Dark Gray and Green",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "center top"
      ],
      "additional_backgrounds_tiling": [
        "no-repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(17, 17, 17)",
      "toolbar_text": "rgb(251, 251, 254)",
      "frame": "rgb(0, 0, 0)",
      "tab_background_text": "rgb(128, 128, 128)",
      "toolbar_field": "rgb(22, 22, 22)",
      "toolbar_field_text": "rgb(251, 251, 254)",
      "tab_line": "rgb(80, 80, 80)",
      "popup": "rgb(17, 17, 17)",
      "popup_text": "rgb(128, 128, 128)",
      "button_background_active": "rgb(80, 80, 80)",
      "button_background_hover": "rgb(64, 128, 64)",
      "icons_attention": "rgb(255, 69, 0)",
      "icons": "rgb(251, 251, 254)",
      "ntp_background": "rgb(22, 22, 22)",
      "ntp_text": "rgb(251, 251, 254)",
      "popup_border": "rgb(80, 80, 80)",
      "tab_selected": "rgb(22, 22, 22)",
      "tab_text": "rgb(251, 251, 254)",
      "toolbar_bottom_separator": "rgb(17, 17, 17)",
      "toolbar_field_border_focus": "rgb(22, 22, 22)",
      "toolbar_field_border": "rgb(0, 0, 0)",
      "toolbar_field_focus": "rgb(0, 0, 0)",
      "toolbar_field_highlight_text": "rgb(251, 251, 254)",
      "toolbar_field_highlight": "rgb(64, 128, 64)",
      "toolbar_field_text_focus": "rgb(251, 251, 254)",
      "toolbar_top_separator": "rgb(17, 17, 17)",
      "tab_loading": "rgb(80, 80, 80)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{d7f8805f-2aa8-46c2-94e8-9714502f00f0}"
    }
  }
}