rails--rails/app/views/active_storage/blobs/_blob.html.erb

<figure class="attachment attachment--<%= blob.representable? ? "preview" : "file" %> attachment--<%= blob.filename.extension %>">
  <% if blob.variable? %>
    <%= image_tag blob.variant(resize: "1024x768>") %>
  <% elsif blob.previewable? %>
    <%= image_tag blob.preview(resize: "1024x768>") %>
  <% end %>

  <figcaption class="attachment__caption">
    <% if caption = blob.try(:caption) %>
      <%= caption %>
    <% else %>
      <span class="attachment__name"><%= blob.filename %></span>
      <span class="attachment__size"><%= number_to_human_size blob.byte_size %></span>
    <% end %>
  </figcaption>
</figure>