projekteuler/app/views/layouts/_header.html.erb

<%= navbar position: :static do %>
    <%= vertical do %>
        <%= link_to t(:site_title), root_path %>
    <% end %>
    <%= horizontal do %>
        <%= nav class: 'navbar-left' do %>
            <%= link_to t('application.info'), about_info_path %>
            <%= link_to Problem.model_name.human(count: 2), problems_path %>
            <% if admin_signed_in? %>
                <%= link_to t('admin.dashboard.index.administration'), :admin %>
            <% end %>
        <% end %>
        <%= nav class: 'navbar-right' do %>
            <%= link_to t('application.legal'), about_legal_path %>
            <% if admin_signed_in? %>
                <%= link_to(t('application.sign_out'), destroy_admin_session_path, method: :delete) %>
            <% else %>
                <%= link_to(t('application.sign_in'), new_admin_session_path) %>
            <% end %>
        <% end %>
    <% end %>
<% end %>