chrome/browser/resources/bluetooth_internals/value_control.html

<style>
  :host {
    display: block;
  }

  div {
    display: flex;
    margin: 4px 0;
  }

  div > input {
    flex-grow: 1;
  }

  div:nth-of-type(2) {
    justify-content: flex-end;
  }

  h3 {
    font-weight: normal;
    line-height: 1;
    user-select: none;
  }
</style>
<h3>Value cannot be read or written</h3>
<div>
  <input></input>
  <select>
    <option value="Hexadecimal">Hexadecimal</option>
    <option value="UTF-8">UTF-8</option>
    <option value="Decimal">Decimal</option>
  </select>
</div>
<div>
  <button class="read">Read</button>
  <button class="write">Write</button>
</div>