Bulma class: .list-item.is-active

<div class="list is-hoverable">
  <a class="list-item">
    Featured
  </a>
  <a class="list-item">
    All Posts
  </a>
  <a class="list-item is-active">
    Announcements
  </a>
  <a class="list-item">
    Business
  </a>
  <a class="list-item">
    Community
  </a>
  <a class="list-item">
    Data
  </a>
  <a class="list-item">
    Editor Tools
  </a>
  <a class="list-item">
    Education
  </a>
  <a class="list-item">
    Engineering
  </a>
  <a class="list-item">
    Events
  </a>
  <a class="list-item">
    Policy
  </a>
</div>