<ul class="nav">
  <li class="nav-item"><a class="nav-link" href="#">Home</a></li>
  <li class="nav-item"><a class="nav-link" href="#">About</a></li>
  <li class="nav-item"><a class="nav-link" href="#">Service</a></li>
  <li class="nav-item"><a class="nav-link" href="#">Team</a></li>
</ul>

body {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
}