JSFiddle - React, Tailwind, and code Playground

HTML

<section id="topmenu">
  <nav id="menu">
    <ul><!-- 
    --><li><a href="#">Lien</a></li><!-- 
    --><li><a href="#">Lien</a></li><!-- 
    --><li><a href="#">Lien</a></li><!-- 
    --><li><a href="#">Lien</a></li>
    </ul>
  </nav>
</section>

CSS

#topmenu {
  background: rgb(166,226,46);
  border-bottom: thin solid #aaa;
  border-top: thin solid rgba(255,255,255,.5);
}

#menu {
  font-size: 1.4rem;
}

#menu ul {
  height: 34px;
}

#menu li {
  display: inline;
  line-height: 34px;
  margin: 0;
}
#menu li:before { 
  content: ""; 
  border-right: thin solid rgba(0,0,0,.2);
  text-shadow: 0 -1px 0 rgba(0,0,0,.5);
  -webkit-box-shadow: 1px 0 0 rgba(255,255,255,.5);
  -moz-box-shadow: 1px 0 0 rgba(255,255,255,.5);
  -ms-box-shadow: 1px 0 0 rgba(255,255,255,.5);
  -o-box-shadow: 1px 0 0 rgba(255,255,255,.5);
  box-shadow: 1px 0 0 rgba(255,255,255,.5);
}
#menu li:first-child:before {
  content:none;
}

#menu li a {
  margin: 0;
  color: #fff;
  padding: 0.75rem 1rem;
}
#menu li a:hover {
  background: #aaa;
}

#menu li:last-of-type a {
  border-right: none;
  -webkit-box-shadow: none;
  -moz-box-shadow: none;
  -ms-box-shadow: none;
  -o-box-shadow: none;
  box-shadow: none;
}