file css
#menu a { border-bottom: 1px solid #ddd; padding: 1em; font-family: "Verdana"; font-size: 15px; display: block; text-decoration:none;}
#menu a:hover{background:#FF0000;}
.active{background-color: #000000;}
file html
<div id="menu">
<li><a href="#page1" class="active" >Scopri Grend</a></li>
<li><a href="#page2" >Accedi</a></li>
<li><a href="#page3" >Registrati</a></li>
<li><a href="#page4" >Contattaci</a></li>
</div>

Risultato
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