app/views/devise/sessions/new.html.erb
<% content_for :breadcrumb do %>
<ol class="breadcrumb">
<li class="active"><%= _('Sign in') %></li>
</ol>
<% end %>
<%= form_for(resource, as: resource_name, url: session_path(resource_name), html: {role: 'form'}) do |f| %>
<div class="form-group">
<%= f.label :email %>
<%= f.email_field :email, autofocus: true, class: 'form-control' %>
</div>
<div class="form-group">
<%= f.label :password %>
<%= f.password_field :password, autocomplete: 'off', class: 'form-control' %>
</div>
<div class="sign-in">
<%= f.button _('Sign in'), class: 'btn btn-primary' %>
<label>
<%= f.check_box :remember_me %> <%= _('Remember me') %>
</label>
<%= link_to _('Forgot password?'), new_password_path(resource_name) %>
</div>
<% end %>