here is application.html.erb
<!DOCTYPE html>
<html>
<head>
<title>Social</title>
<%= stylesheet_link_tag 'application', media: 'all', 'data-turbolinks-track' => true %>
<%= javascript_include_tag 'application', 'data-turbolinks-track' => true %>
<%= csrf_meta_tags %>
</head>
<body>
<%= render 'shared/navbar' %>
<%= render 'shared/messages' %>
<div class="container">
<%= yield %>
</div>
</body>
</html>
_shared/navbar.html.erb
<nav class="navbar navbar-default navbar-fixed-top">
<div class="container">
<div class="navbar-header">
<%= link_to 'Social', root_path, class: 'navbar-brand' %>
</div>
<div id="navbar">
<ul class="nav navbar-nav">
<li><%= link_to 'Home', root_path %></li>
<li><%= link_to 'Trending', "#" %></li>
</ul>
<ul class="nav navbar-nav pull-right">
<% if user_signed_in? %>
<li class="dropdown">
<a class="dropdown-toggle" data-toggle="dropdown" href="#">
<%= current_user.email %>
<span class="caret"></span>
</a>
<ul class="dropdown-menu" role="menu">
<li><%= link_to 'Profile', edit_user_registration_path %></li>
<li><%= link_to 'Log out', destroy_user_session_path, method: :delete %></li>
</ul>
</li>
<% else %>
<li><%= link_to 'Log In', new_user_session_path %></li>
<li><%= link_to 'Sign Up', new_user_registration_path %></li>
<% end %>
</ul>
</div>
</div>
</nav>
_shared/messages.html.erb
<div class="container">
<% flash.each do |key, value| %>
<div class="alert alert-<%= key %>">
<%= value %>
<button type="button" class="close" data-dismiss="alert" aria-hidden="true">×</button>
</div>
<% end %>
</div>
style.css
body {
padding-top: 100px;
font-family: 'Noto Sans', sans-serif;
}
.alert-alert {
@extend .alert-warning;
}
.alert-notice {
@extend .alert-info;
}