app/views/layouts/doorkeeper/admin.html.erb
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title><%= t('doorkeeper.layouts.admin.title') %></title>
<%= stylesheet_link_tag "doorkeeper/admin/application" %>
<%= csrf_meta_tags %>
</head>
<body>
<nav class="navbar navbar-expand-lg navbar-dark bg-dark mb-5">
<%= link_to t('doorkeeper.layouts.admin.nav.oauth2_provider'), oauth_applications_path, class: 'navbar-brand' %>
<div class="collapse navbar-collapse">
<ul class="navbar-nav mr-auto">
<li class="nav-item <%= 'active' if request.path == oauth_applications_path %>">
<%= link_to t('doorkeeper.layouts.admin.nav.applications'), oauth_applications_path, class: 'nav-link' %>
</li>
<% if respond_to?(:root_path) %>
<li class="nav-item">
<%= link_to t('doorkeeper.layouts.admin.nav.home'), root_path, class: 'nav-link' %>
</li>
<% end %>
</ul>
</div>
</nav>
<div class="doorkeeper-admin container">
<%- if flash[:notice].present? %>
<div class="alert alert-info">
<%= flash[:notice] %>
</div>
<% end -%>
<%= yield %>
</div>
</body>
</html>