<div style="width: 100%; max-width: 728px; height: 90px; background-color: #f2f2f2; text-align: center;">
  <a href="https://www.example.com" target="_blank">
    <img src="https://www.example.com/banner-image.jpg" alt="Banner Image" style="max-width: 100%; max-height: 100%;">
  </a>
</div>