<form class="usa-form">
  <fieldset class="usa-fieldset">
    <legend class="usa-legend usa-legend--large">Enter a code</legend>
    <div class="usa-alert usa-alert--info usa-alert--validation">
      <div class="usa-alert__body">
        <h3 class="usa-alert__heading">Code requirements</h3>
        <ul class="usa-checklist" id="validate-code">
          <li class="usa-checklist__item" data-validator="uppercase">Use at least one uppercase character</li>
          <li class="usa-checklist__item" data-validator="numerical">Use at least one number</li>
        </ul>
      </div>
    </div>
    <label class="usa-label" for="code">Code</label>
    <input class="usa-input" id="code" name="code" type="text" data-validate-uppercase="[A-Z]" data-validate-numerical="\d" data-validation-element="validate-code">
    <input class="usa-button" type="submit" value="Submit code">
  </fieldset>
</form>
