Examine source code of Gothangel

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Gothangel",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "right top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(104, 106, 106)",
      "toolbar_text": "rgb(238, 244, 244)",
      "frame": "rgb(112, 112, 112)",
      "tab_background_text": "rgb(230, 234, 234)",
      "toolbar_field": "rgb(72, 74, 74)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(255, 255, 255)",
      "popup": "rgb(64, 64, 64)",
      "popup_text": "rgb(140, 140, 140)",
      "button_background_hover": "rgb(179, 184, 184)",
      "ntp_background": "rgb(135, 135, 135)",
      "sidebar_highlight_text": "rgb(255, 255, 255)",
      "tab_background_separator": "rgb(255, 255, 255)",
      "tab_selected": "rgb(66, 66, 66)",
      "toolbar_field_highlight_text": "rgb(238, 241, 241)",
      "toolbar_top_separator": "rgb(238, 244, 244)",
      "toolbar_vertical_separator": "rgb(255, 255, 255)",
      "tab_loading": "rgb(255, 255, 255)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{52474657-6a96-4ebb-abe7-26deebed2b6c}"
    }
  }
}