Header navigation - no JavaScript

HTML

<header data-module="govuk-header" class="dwp-header">
  <div class="dwp-header__content govuk-width-container">
    <div class="dwp-header__service-name">
      <a href="#" class="dwp-header__link">Service name</a>
    </div>
    <nav class="dwp-header-navigation"
      aria-label="Primary">
      <ul id="navigation" class="dwp-header-navigation__list">
        <li class="dwp-header-navigation__item">
          <a
            href="#">
            Find someone
          </a>
        </li>
        <li class="dwp-header-navigation__item">
          <a
            href="#">
            Tasks
          </a>
        </li>
        <li class="dwp-header-navigation__item">
          <a
            href="#">
            Telephone claim
          </a>
        </li>
        <li class="dwp-header-navigation__item">
          <a
            href="#">
            Paper claim
          </a>
        </li>
        <li class="dwp-header-navigation__item">
          <a
            href="#">
            Admin
          </a>
        </li>
      </ul>
    </nav>
  </div>
</header>