app/views/layouts/_header.html.erb
<header class="navbar navbar-inverse">
<div class="container">
<%= link_to "Task Tool", root_path,class: "navbar-brand" %>
<nav>
<ul class="nav navbar-nav navbar-right">
<li><%= link_to t("default.home"),root_path,class: "nav-link" =%></li>
<li><%= link_to t("default.help") %></li>
<% if user_signed_in? %>
<li><%= link_to t("default.logout"),destroy_user_session_path, method: :delete %></li>
<% else %>
<li><%= link_to t("default.signup"),new_user_registration_path %></li>
<li><%= link_to t("default.login"),new_user_session_path %></li>
<% end %>
</ul>
</nav>
</div>
</header>