chromium/chrome/browser/resources/bluetooth_internals/descriptor_list_item.html

<style>
  :host {
    --brief-content-background-color: var(--darker-primary-color);
  }

  .info-container > h4,
  .info-container > object-field-set,
  .info-container > value-control {
    margin: 1em;
  }
</style>
<expandable-list-item>
  <div slot="brief-content">
    <div>Descriptor:</div>
    <div class="header-value"></div>
  </div>
  <div slot="expanded-content" class="info-container">
    <h4>Descriptor Info</h4>
    <object-field-set show-all hidden></object-field-set>
    <h4>Value</h4>
    <value-control hidden></value-control>
  </div>
</expandable-list-item>