nav.html

<nav class="navbar navbar-expand-md navbar-dark bg-dark mb-4">
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarCollapse"
          aria-controls="navbarCollapse" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>
  <div class="collapse navbar-collapse" id="navbarCollapse">
    <ul class="navbar-nav mr-auto">
      <li class="nav-item active">
        <a class="nav-link" href="index.html">Home</a>
      </li>
      <li class="nav-item active">
        <a class="nav-link" href="publications.html">Publications</a>
      </li>
      <li class="nav-item active">
        <a class="nav-link" href="teaching.html">Teaching</a>
      </li>
    </ul>
    <!--        <form class="form-inline mt-2 mt-md-0">-->
    <!--            <input class="form-control mr-sm-2" type="text" placeholder="Search" aria-label="Search">-->
    <!--            <button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>-->
    <!--        </form>-->
  </div>
</nav>