Your standard form button.
This block above was created with a simple template call:
<% styleguide_block '1.1' do %>
<button class="$modifier_class">Example Button</button>
<% end %>
Take a look at the source code to this Sinatra app for more details. The goal is to remove the pain from creating a styleguide — document your CSS, have example HTML in your templates and automate as much as possible.