app/views/shared/_metadata.html.erb
<!-- Uncomment to make IE8 render like IE7 -->
<!-- <meta http-equiv="X-UA-Compatible" content="IE=7" /> -->
<!-- Set the viewport width to device width for mobile -->
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<meta charset="utf-8" />
<% if content_for?(:metadata) %>
<%= yield :metadata %>
<% else %>
<%# Add your default metadata here %>
<meta name="keywords" content="<%= I18n.t(:meta_keywords) %>">
<meta name="description" content="<%= I18n.t(:meta_description) %>">
<% end %>