gateway/app/views/layouts/application.html.haml

!!!
%html
  %head
    %meta{:content => "text/html; charset=UTF-8", "http-equiv" => "Content-Type"}/
    %title Gateway
    %meta{:content => "width=device-width,initial-scale=1", :name => "viewport"}/
    = csrf_meta_tags
    = csp_meta_tag
    = stylesheet_link_tag "application"
    = javascript_include_tag "application",  defer: true 
  %body
    = yield