Sinatra layouts vs templates

I must have missed this on my first pass of the Sinatra (sinatrarb) book. There is a very nice way to create a site template, called a layout.

Just create a file in views called layout.erb (or layout.haml if using haml) output yield where you want the body of the templates to be inserted. Class @variables can also be used.
This allows the basic layout of your site Headers, Footers and navigation panes to be controlled independently, a change in layout.erb is instantly applied across your whole site.

layout.erb

< h t m l>
   < h e a d>
      < t i t l e><%= @title %>< / t i t l e>
   < / h e a d>
   < b o d y>
      <%= yield %>
   < / b o d y>
< / h t m l>

you app.rb (NB: no refference to layour.erb is made)

get '/about/?' do
   @title = "About"
   erb :about
end

/views/about.erb

<p>Example about page</p>