anchor.diff:    <head>
       <meta charset="utf-8">
       <title>${ title }</title>
  +
       <link rel="stylesheet" href="${ pageContext.request.contextPath }/resources/font-awesome/css/font-awesome.css">
       <link rel="stylesheet" href="${ pageContext.request.contextPath }/resources/marketplace/css/marketplace-grid.css">
       <link rel="stylesheet" href="${ pageContext.request.contextPath }/resources/marketplace/css/marketplace-theme.css">
       <link rel="stylesheet" href="${ pageContext.request.contextPath }/resources/marketplace/css/marketplace-helpers.css">
     </head>
     <body>
  -  <div class="navbar navbar-fixed-top">
  -    <div class="container-fluid">
  +    <div class="navbar navbar-fixed-top">
  +      <div class="container-fluid">
   
  -      <div class="navbar-header">
  -        <a class="navbar-brand" href="${ pageContext.request.contextPath }">WMarket</a>
  -      </div><!-- /.navbar-header -->
  +        <div class="navbar-header">
  +          <a class="navbar-brand" href="${ pageContext.request.contextPath }">WMarket</a>
  +        </div><!-- /.navbar-header -->
   
  -      <form class="navbar-element pull-left">
  -        <div class="form-field">
  -          <button id="toggle-left-sidebar" class="btn btn-default btn-addon" type="button">
  -            <span class="fa fa-bars"></span>
  -          </button>
  -          <input id="search-field" class="form-control" type="text" placeholder="Search for offerings">
  -          <button id="search" class="btn btn-default btn-addon" type="submit">
  -            <span class="fa fa-search"></span>
  -          </button>
  -        </div>
  -      </form><!-- /.navbar-element -->
  +        <form class="navbar-element pull-left">
  +          <div class="form-field">
  +            <button id="toggle-left-sidebar" class="btn btn-default btn-addon" type="button">
  +              <span class="fa fa-bars"></span>
  +            </button>
  +            <input id="search-field" class="form-control" type="text" placeholder="TODO: Not implemented yet.">
  +            <button id="search" class="btn btn-default btn-addon" type="submit">
  +              <span class="fa fa-search"></span>
  +            </button>
  +          </div>
  +        </form><!-- /.navbar-element -->
   
  -      <div class="navbar-element pull-right">
  -        <button id="toggle-right-sidebar" class="btn btn-primary-lighter" type="submit">
  -          <span class="fa fa-user"></span>
  -          <span class="text-plain text-truncate hidden-smartphone">${ user.displayName }</span>
  -        </button>
  -      </div><!-- /.navbar-element -->
  +        <c:choose>
  +          <c:when test="${ not empty user }">
   
  -    </div>
  -  </div><!-- /.navbar -->
  +            <div class="navbar-element pull-right">
  +              <button id="toggle-right-sidebar" class="btn btn-primary-lighter" type="submit">
  +                <span class="fa fa-user"></span>
  +                <span class="text-plain text-truncate hidden-smartphone">${ user.displayName }</span>
  +              </button>
  +            </div><!-- /.navbar-element -->
   
  -    <div id="right-sidebar" class="panel panel-default-darker panel-sliding panel-sliding-right">
  -    <div class="panel-heading">
  -      <span class="fa-avatar fa-stack">
  -        <i class="fa fa-circle fa-stack-2x"></i>
  -        <i class="fa fa-user fa-stack-1x fa-inverse"></i>
  -      </span>
  -      <span class="panel-title text-truncate">${ user.displayName }</span>
  -      <span class="panel-subtitle text-truncate">${ user.email }</span>
  -    </div>
  -    <div class="panel-body">
  -      <div class="list">
  -        <div class="list-body">
  -          <a class="list-item" href="#">
  -            <i class="fa fa-cog fa-fw"></i>&nbsp; Settings
  -          </a>
  -          <a class="list-item" href="#">
  -            <i class="fa fa-sign-out fa-fw"></i>&nbsp; Sign out
  -          </a>
  -        </div>
  -        </div>
  +          </c:when>
  +        </c:choose>
  +
         </div>
  -    </div><!-- /.panel -->
  +    </div><!-- /.navbar -->
  +
  +    <c:choose>
  +      <c:when test="${ not empty user }">
  +
  +        <div id="right-sidebar" class="panel panel-default-darker panel-sliding panel-sliding-right">
  +          <div class="panel-heading">
  +            <span class="fa-avatar fa-stack">
  +              <i class="fa fa-circle fa-stack-2x"></i>
  +              <i class="fa fa-user fa-stack-1x fa-inverse"></i>
  +            </span>
  +            <span class="panel-title text-truncate">${ user.displayName }</span>
  +            <span class="panel-subtitle text-truncate">${ user.email }</span>
  +          </div>
  +          <div class="panel-body">
  +            <div class="list">
  +              <div class="list-body">
  +                <a class="list-item" href="#">
  +                  <i class="fa fa-cog fa-fw"></i>&nbsp; Settings
  +                </a>
  +                <a class="list-item" href="#">
  +                  <i class="fa fa-sign-out fa-fw"></i>&nbsp; Sign out
  +                </a>
  +              </div>
  +            </div>
  +          </div>
  +        </div><!-- /.panel -->
  +
  +      </c:when>
  +    </c:choose>
   
       <t:insertAttribute name="left-sidebar" ignore="true" />
       <t:insertAttribute name="content" />
  
positive.code:     </div><!-- /.footer -->
  
      <script src="${ pageContext.request.contextPath }/resources/jquery/js/jquery-1.11.2.js"></script>
      <script src="${ pageContext.request.contextPath }/resources/marketplace/js/Store.js"></script>
      <script src="${ pageContext.request.contextPath }/resources/marketplace/js/Offering.js"></script>
      <t:insertAttribute name="extra-scripts" />
    </body>
  </html>
  
negative.code: <%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %>
  
  <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
  <%@ taglib prefix="t" uri="http://tiles.apache.org/tags-tiles" %>
  
  <!DOCTYPE html>
  