app/views/devise/sessions/_form.html.erb
<%= form_for(resource, as: resource_name, url: session_path(resource_name)) do |f| %>
<div class="field">
<%= f.label :email %><br />
<%= f.email_field :email, autofocus: true %>
</div>
<div class="field">
<%= f.label :password %><br />
<%= f.password_field :password, autocomplete: "off" %>
</div>
<div class="spacer"> </div>
<div class="actions center">
<div class="col s6">
<% if devise_mapping.rememberable? -%>
<%= f.label :remember_me do %>
<%= f.check_box :remember_me %>
<span>Remember me</span>
<% end %>
<% end -%>
</div>
<div class="col s6">
<%= f.submit "Log in", class: 'btn blue' %>
</div>
<p class="center">
<br />
<%= render "devise/shared/links" %>
</p>
</div>
<% end %>