ul.dropdown,ul.dropdown li,ul.dropdown ul {/* */  
    list-style: none; 
	
}
ul.dropdown { /* le menu complet*/  
	position: relative; 
	z-index: 597; 
	float: left;
	border: px solid red ;
}
ul.dropdown li { /*les onglets du menu */  
	float: left; 
	line-height: 1.3em; 
	vertical-align: middle; 
	border: px solid red ;
}
ul.dropdown li.hover,ul.dropdown li:hover { /*au passage de la souris, met en relief l'onglet */  
    position: relative;
    z-index: 599; 
    cursor: default;
	border: px solid red ;
}
ul.dropdown ul { /* le menu deroulant*/  
    visibility: hidden; 
    position: absolute; 
    top: 100%; left: 0; 
    z-index: 598;
    width: 100%;
	border: px solid red ;
}
ul.dropdown ul li { /* les onglets du menu deroulant*/  
    float: none;
	border: px solid red ;
}

ul.dropdown li:hover > ul { /*visibilité du menu deroulant*/  
    visibility: visible;
}