app/views/devise/registrations/new.html.erb
<% header "Sign Up" %>
<%= form_for(resource, as: resource_name, url: registration_path(resource_name)) do |f| %>
<%= devise_error_messages! %>
<div class="form-group">
<%= f.label :username %>
<%= f.text_field :username, class: 'form-control' %>
</div>
<div class="form-group">
<%= f.label :email %>
<%= f.email_field :email, class: 'form-control' %>
</div>
<div class="form-group">
<%= f.label :password %>
<%= f.password_field :password, autocomplete: "off", class: 'form-control' %>
<% if @validatable %>
<span class="help-block"><%= @minimum_password_length %> characters minimum</span>
<% end %>
</div>
<div class="form-group">
<%= f.label :password_confirmation %>
<%= f.password_field :password_confirmation, autocomplete: "off", class: 'form-control' %>
</div>
<%= f.submit "Sign up", class: 'btn btn-primary' %>
<% end %>
<%= render "devise/shared/links" %>