#ca{
margin:auto;
width:200px;
}

ul,ol{
list-style:none;
}
			
.nav .des a{
background-color:#000;
color:#fff;
text-decoration:none;
padding:10px 15px;
display:block;
}

.nav .des a:hover{
background-color:#434343;
}

.nav .des>ul{
float:left;
}

.nav .des ul{
display:none;
position:absolute;
min-width:200px;
}

.nav .des:hover >ul{
display:block;
}