app/views/session/create.html.erb
<div class="text-center my-4 pt-5">
<h1 class="h3 mb-0 mt-0 pt-5 font-weight-bold">Anmeldung</h1>
</div>
<%= form_tag( log_in_path , method: :post) do |f| %>
<div class="form-group row justify-content-center">
<label for="exampleInputEmail1" class="col-lg-2 col-form-label">E-Mail-Adresse</label>
<div class="col-lg-5">
<%= text_field_tag(:email, "", class: "form-control", placeholder: "E-Mail eingeben") %>
</div>
</div>
<div class="form-group row justify-content-center">
<label for="exampleInputPassword1" class="col-lg-2 col-form-label">Passwort</label>
<div class="col-lg-5">
<%= password_field_tag(:password, "", class: "form-control", placeholder: "Passwort eingeben") %>
</div>
</div>
<div class="row justify-content-center mt-5">
<button type="submit" class="btn btn-primary">Anmelden</button>
</div>
<% end %>