<div class="navbar navbar-default">
  <div class="container">
    <div class="navbar-header">
      <button type="button" class="navbar-toggle" data-toggle="collapse"
        data-target=".navbar-collapse">
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
      </button>
    </div>
    <div class="navbar-collapse collapse">
      <ul class="nav navbar-nav">
        <li class="<%= active?(home_path) %>">
          <%= link_to "Home", home_path %>
        </li>
        <li class="<%= active?(/^\/browse/, request.path) %>">
          <%= link_to "Browse", browse_path %>
        </li>
        <li class="<%= active?(search_path) %>">
          <%= link_to "Search", search_path %>
        </li>
        <li class="<%= active?(about_path) %>">
          <%= link_to "About", about_path %>
        </li>
      </ul>
    </div>
  </div>
</div><!-- /navbar -->

<div class="navbar navbar-default">
  <div class="container">
    <div class="navbar-header">
      <button type="button" class="navbar-toggle" data-toggle="collapse"
        data-target=".navbar-collapse">
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
      </button>
    </div>
    <div class="navbar-collapse collapse">
      <ul class="nav navbar-nav">
        <li class="<%= active?(home_path) %>">
          <%= link_to "Home", home_path %>
        </li>
        <li class="<%= active?(/^#{config.relative_url_root}\/browse/,
          request.path) %>">
          <%= link_to "Browse", browse_path %>
        </li>
        <li class="<%= active?(search_path) %>">
          <%= link_to "Search", search_path %>
        </li>
        <li class="<%= active?(about_path) %>">
          <%= link_to "About", about_path %>
        </li>
      </ul>
    </div>
  </div>
</div><!-- /navbar -->

Update Browse active? check to consider sub-URI
Update Browse active? check to consider sub-URI
