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

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

  .info-container > h4,
  .info-container > object-field-set {
    margin: 1em;
  }

  h3 {
    font-weight: normal;
    line-height: 1;
    user-select: none;
  }
</style>
<expandable-list-item>
  <div slot="brief-content">
    <div>Service:</div>
    <div class="header-value"></div>
  </div>
  <div slot="expanded-content" class="info-container">
    <h4>Service Info</h4>
    <object-field-set hidden show-all></object-field-set>
    <h4>Characteristics</h4>
    <characteristic-list></characteristic-list>
  </div>
</expandable-list-item>