govuk-frontend/dist/govuk/components/input/template-with-error-message.html

GOV.UK Frontend contains the code you need to start building a user interface for government platforms and services.

<div class="govuk-form-group govuk-form-group--error">
  <label class="govuk-label" for="input-with-error-message">
    National Insurance number
  </label>
  <p id="input-with-error-message-error" class="govuk-error-message">
    <span class="govuk-visually-hidden">Error:</span> Enter a National Insurance number in the correct format
  </p>
  <input class="govuk-input govuk-input--error" id="input-with-error-message" name="test-name-3" type="text" aria-describedby="input-with-error-message-error">
</div>