app/views/devise/sessions/new.html.erb
<header>
<h1>Sign in</h1>
</header>
<%= simple_form_for(resource, as: resource_name, url: session_path(resource_name), html: {id: 'new_session'}) do |f| %>
<div class="data_collection_form">
<fieldset>
<div class="pill_wrap">
<%= f.input :email, placeholder: 'jon@doe.com', label: 'email', required: false %>
</div>
<div class="pill_wrap">
<%= f.input :password %>
</div>
</fieldset>
</div>
<div class="controls">
<%= f.input :remember_me, as: :hidden, input_html: {value: 1} %>
<%= f.button :submit, 'Sign in', :class => 'cta-pill' %>
<%= render 'devise/shared/links' %>
</div>
<% end %>