discourse/plugins/chat/assets/stylesheets/desktop/chat-composer-uploads.scss

.chat-composer-uploads {
  .chat-composer-uploads-container {
    .full-page-chat & {
      flex-wrap: wrap;
      row-gap: 0.5rem;
    }
  }
}

.chat-composer-dropdown__trigger-btn {
  align-self: flex-end;
  height: 50px;
}