No JavaScript

HTML

<div class="govuk-notification-banner govuk-notification-banner--blue" role="region" aria-labelledby="govuk-notification-banner-title" data-module="govuk-notification-banner">
  <div class="govuk-notification-banner__header">
    <h2 class="govuk-notification-banner__title" id="govuk-notification-banner-title">
      Important
    </h2>
  </div>
  <div class="govuk-notification-banner__content">
    <div class="govuk-body">
      <p>We will delete your answers if you do not do anything for <strong>20 minutes</strong> and you will have to start again. This is to protect your information.</p>
    </div>
  </div>
</div>