Maybe/app/views/shared/_auth_messages.html.erb

<% flash.each do |type, msg| %>
  <div class="p-4 <%= type == "notice" ? "bg-blue-200" : "bg-red-200" %> rounded-lg"><%= msg %></div>
<% end %>

<% errors.each do |message| %>
  <div class="p-4 bg-red-200 rounded-lg"><%= message %></div>
<% end %>