Trouble styling wp_list_pages

Hi,

I’m trying to make a horizontal menu with wp_list_pages in my blog. I’m styling it so the main navigation shows in one line and the subnavigation in one line under it. And I want to show the subnavigation only at the pages it belongs to. I’m trying to do it with the classes current_page_parent and current_page_itm, but it’s not working.

Here’s my css:

#nav {
	position:absolute;
	left: 220px;
	width: 530px;
	height: 41px;
	padding-top: 39px;
}
#nav li { /*float the main list items*/
	float: left;
	display: block;
}
#nav li.page_item a { /*style the main nav links*/
	display: block;
	font: 100% "Arial Narrow", Arial, Verdana, Helvetica, sans-serif;
}
#nav li.page_item current_page_parent a { /*highlight the actual section - isn't working*/
	color: #FFF;
}
#nav li.page_item ul li.page_item{ /*put the subnav below and hide them all*/
	display: none;
	position: absolute;
	height: 15px;
	left: 0;
	padding-top: 5px;
}
#nav li.page_item ul li.page_item a { /*style the subnav links*/
	font: 70% Arial, Verdana, Helvetica, sans-serif;
	padding: 0 6px 0 6px;
	border-right: 1px solid #CCC;
}
#nav li.page_item ul li.page_item a:hover{ /*style the subnav links*/
	border-bottom: 3px solid #FFF;
}
#nav li.page_item current_page_parent ul li.page_item current_page_item { /*show only the subnav of the current section - isn't working*/
	display: block;
}

And the code:

<ul id="nav">
	<li class="page_item"><a href="https://localhost/wordpress/?page_id=2" title="Biografia">Biografia</a></li>
	<li class="page_item current_page_parent"><a href="https://localhost/wordpress/?page_id=13" title="Cotidiano">Cotidiano</a>
		<ul>
		<li class="page_item current_page_item"><a href="https://localhost/wordpress/?page_id=17" title="Dia-a-dia">Dia-a-dia</a></li>
		</ul>
	</li>
	<li class="page_item"><a href="https://localhost/wordpress/?page_id=14" title="Pessoais">Pessoais</a>
		<ul>
		<li class="page_item"><a href="https://localhost/wordpress/?page_id=19" title="Festa do Divino">Festa do Divino</a></li>
		<li class="page_item"><a href="https://localhost/wordpress/?page_id=18" title="Las Cholas">Las Cholas</a></li>
		</ul>
	</li>
	<li class="page_item"><a href="https://localhost/wordpress/?page_id=15" title="Publica??es">Publica??es</a>
		<ul>
		<li class="page_item"><a href="https://localhost/wordpress/?page_id=20" title="Capas">Capas</a></li>
		</ul>
	</li>
	<li class="page_item"><a href="https://localhost/wordpress/?page_id=16" title="Contato">Contato</a></li>
</ul>

Could somebody help, me please!

Thanks,
Cátia