Sous menu horizontal

div#menu {
 font: 11px verdana, sans-serif;
 background:url("http://dungeon-rpg.com/test-pic/shining/shining.jpg") no-repeat scroll center top #FFFFFF;;
 margin: 0 ;
 padding: 0;
 height: 100px;
}

#menu                   
{
	width:520px;          
	height: auto;          
	list-style-type: none;  
	margin: 0 auto;      
	padding: 0;       
	border: 0;      
	
	}
#menu > li            
{
	float: left;          
	width: 120px;          
	margin: 5px;          
	padding: 0;
	border: 0;
}
#menu li a
{
	display: block;       
	color: #FFFFFF;         
      background-color: rgb(0, 0, 0);        
	background-color: rgba(0, 0, 0, 0.5);    
	margin: 0;                               
	padding: 4px 8px;                      
	height: 120px;
	border:1px solid #FFFFFF;              
	text-decoration: none;         

}

#menu li a:hover {                       
      background-color: rgb(175, 214, 1);
      background-color: rgba(175, 214, 1, 0.5);
}

#menu .menuderoulant   
{
	display: none;          
	list-style-type: none;  
	margin: 0;           
	padding: 0;
	border: 0;
}
#menu .menuderoulant li         
{
	margin: 0;
	padding: 0;
	border: 0;
	width: 120px;               
      border-top: 1px solid transparent;      
	border-right: 1px solid transparent;
}
#menu .menuderoulant li a   
{
	display: block;
	color: #FFF;
	margin: 0;
	border: 0;
	text-decoration: none;       
      background-color:rgb(0, 0, 0);
      background-color:rgba(0,0,0,0.5);

}
#menu .menuderoulant li a:hover      
{
	background-color: rgb(18, 89, 239);
      background-color: rgba(18, 89, 239, 0.8);

}

#menu .menuderoulant li a:visited {        
      background-color:rgb(227, 22, 30);
      background-color:rgba(227, 22, 30, 0.5);
}

#menu li:hover > .menuderoulant { display: block; }  

<div id="menu">
<ul id="menu">

<li>

<a href="#1">Sony</a>

<ul class="menuderoulant">

<li><a href="http://dungeon-rpg.com/?page_id=326">Playstation</a></li>
<li><a href="http://dungeon-rpg.com/playstation-2/">Playstation 2</a></li>
<li><a href="http://dungeon-rpg.com/playstation-3/">Playstation 3</a></li>
<li><a href="http://dungeon-rpg.com/ps-vita/">PS vita</a></li>
<li><a href="http://dungeon-rpg.com/psp/">PSP</a></li>
</ul>

</li>

<li>

<a href="#5">Sega</a>

<ul class="menuderoulant">
<li><a href="http://dungeon-rpg.com/dreamcast/">Dreamcast</a></li>
<li><a href="http://dungeon-rpg.com/megadrive/">Megadrive</a></li>
<li><a href="http://dungeon-rpg.com/saturn/">Saturn</a></li>

</ul>

</li>

<li>

<a href="#21">Nintendo</a>

<ul class="menuderoulant">

<li><a href="http://dungeon-rpg.com/game-boy/">Gameboy</a></li>
<li><a href="http://dungeon-rpg.com/game-boy-advance/">Gameboy advance</a></li>
<li><a href="http://dungeon-rpg.com/280-2/">Gameboy color</a></li>
<li><a href="http://dungeon-rpg.com/gamecube/">Gamecube</a></li>
<li><a href="http://dungeon-rpg.com/nintendo-3ds/">Nintendo 3DS</a></li>
<li><a href="http://dungeon-rpg.com/nintendo-64/">Nintendo 64</a></li>
<li><a href="http://dungeon-rpg.com/ds/">Nintendo DS</a></li>
<li><a href="http://dungeon-rpg.com/nes/">Nintendo NES</a></li>
<li><a href="http://dungeon-rpg.com/super-nintendo/">Super Nintendo</a></li>
<li><a href="http://dungeon-rpg.com/wii/">Wii</a></li>
<li><a href="http://dungeon-rpg.com/wii-u/">Wii U</a></li>
</ul>

</li>

<li>

<a href="#22">Divers</a>

<ul class="menuderoulant">

<li><a href="http://dungeon-rpg.com/cd-i-2/">CD-i</a></li>
<li><a href="http://dungeon-rpg.com/n-gage/">N-Gage</a></li>
<li><a href="http://dungeon-rpg.com/multi-supports/">Multi supports</a></li>
<li><a href="http://dungeon-rpg.com/pc-windows/">PC windows</a></li>
<li><a href="http://dungeon-rpg.com/wonderswan/">Wonderswan</a></li>
<li><a href="http://dungeon-rpg.com/374-2/">Xbox</a></li>
<li><a href="http://dungeon-rpg.com/xbox-360/">Xbox 360</a></li>

</ul>

</li>
</ul>
</div>