app/views/devise/sessions/new.html.erb
<div class="row justify-content-center">
<div class="col-lg-6">
<div class="card">
<div class="card-header text-muted"><%= title t('.sign_in') %></div>
<div class="card-body">
<%= 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, required: true, autocomplete: "email", class: "form-control #{"is-invalid" if resource.errors[:email].any?}" %>
</div>
<div class="form-group">
<span class="<%= pull_end_class %>"><%= link_to t('devise.passwords.new.forgot_your_password'), new_password_path(resource_name) %></span>
<%= f.label :password %>
<%= f.password_field :password, required: true, autocomplete: "current-password", class: "form-control #{"is-invalid" if resource.errors[:password].any?}" %>
</div>
<!--
<% if devise_mapping.rememberable? %>
<div class="form-check">
<%= f.label :remember_me, class: 'form-check-label' do %>
<%= f.check_box :remember_me, class: 'form-check-input' %>
<%= t('.remember_me') %>
<% end %>
</div>
<% end %>
-->
<%= f.submit t('.sign_in'), class: 'btn btn-primary btn-block' %>
<% end %>
</div>
</div>
</div>
</div>