Realiser un menu roll-over css3

<nav id="menu" role="navigation">

    	<ul>

      		<li> <a href="Acceuil.html"class="cellules">Accueil</a></li>

      		<li><a href="Gallerie.html" class="cellules">Galerie</a></li>

      		<li><a href="artistes.html" class="cellules"title="lien">Artistes</a></li>

      		<li><a href="commentaire.php" class="cellules">Commentaires</a></li>

      		<li><a href="contact.php" class="cellules">Contact</a></li>

      		

    	</ul>

  	</nav>

#menu ul {

	text-align: center;

	background-color:#BAF3EB;

	height:40px;

	line-height:40px;

	

background:#BAF3EB;

}

#menu ul li {

	text-align: center;

	display:inline;

	margin-right: 25px;

	margin-left: 25px;

}

#menu ul li a {

  

  color:#333 ;

 

  font:  "Trebuchet MS",Arial,sans-serif ;

  text-align: center ;

  text-decoration: none ;

	}

.cellules li a:hover,.cellules li a:focus, .cellulesli a:active {

  background: #900 ;

  text-decoration:none;

}

.cellules ul li a {

	

	color:#333 ;

 

  font:  "Trebuchet MS",Arial,sans-serif ;

  text-align: center ;

  text-decoration: none ;



	

	text-align: center;

	text-decoration:none;

	

}