JSFiddle - React, Tailwind, and code Playground

HTML

<div id="nav">
  <dl>
    <dd class=""><a id="home" href="http://www.scuderiegranduca.it/" style="color: black;">Categorie</a>
      <ul style="display: none;">
        <li><a href="http://www.scuderiegranduca.it/donna-c-7.html">Donna</a></li>
        <li><a href="http://www.scuderiegranduca.it/uomo-c-1.html">Uomo</a></li>
      </ul>
    </dd>
    <dd class=""><a href="index.php?main_page=account">TUO Account</a></dd>
    <dd class=""><a href="index.php?main_page=privacy">Normativa Privacy</a></dd>
    <dd class=""><a href="index.php?main_page=contact_us">Info &amp; Contatti</a></dd>
  </dl>
</div>

JavaScript

/*	nav	*/

if(document.getElementById("nav")){

	var _obj = document.getElementById("nav").getElementsByTagName("DD");

	for(i=0;i<_obj.length;i++){

		_obj[i].onmouseover=function(){

			this.className="sel";

			var _obj = this.getElementsByTagName("UL")[0];

			if(_obj == null){return;}

			_obj.style.display="block";

			var _obj2 = this.getElementsByTagName("a")[0];

			_obj2.style.color='red';

		}

		_obj[i].onmouseout=function(){

			this.className="";

			var _obj = this.getElementsByTagName("UL")[0];

			if(_obj == null){return;}

			_obj.style.display="none";

			var _obj2 = this.getElementsByTagName("a")[0];

			_obj2.style.color='black';

		}

	}

}