#nav {
width: 820px;
height: 40px;
position: relative;
background: url(../imagenes/menubg.png)!important;
   background-image: none;
   filter: progid:DXImageTransform.Microsoft.AlphaImageLoader (src='imagenes/menubg.png', sizingMethod='image');
margin: 0;
padding: 0;
}

#nav li {
float: left;
}

#nav li a {
position: absolute;
top: 0;
margin: 0;
padding: 0;
display: block;
height: 40px;
background: url(../imagenes/menutototal.jpg) no-repeat;
text-indent: -9999px;
overflow: hidden;
}

/*up state*/
li#nav_inicio a {
left: 21px;
width: 130px;
background-position: -0px 0;
}

li#nav_productos a {
left: 151px;
width: 130px;
background-position: -260px 0;
}

li#nav_medio1 a {
left: 281px;
width: 130px;
background-position: -520px 0;
}

li#nav_medio2 a {
left: 411px;
width: 130px;
background-position: -780px 0;
}

li#nav_contacto a {
left: 541px;
width: 130px;
background-position: -1040px 0;
}

li#nav_compania a {
left: 671px;
width: 130px;
background-position: -1300px 0;
}

li#nav_menuder {
left: 801px;
width: 21px;
background:none;
}

/*hover state*/
li#nav_inicio a:hover {
background-position: -130px 0;
}

li#nav_productos a:hover {
background-position: -390px 0;
}

li#nav_medio1 a:hover {
background-position: -650px 0;
}

li#nav_medio2 a:hover {
background-position: -910px 0;
}

li#nav_contacto a:hover {
background-position: -1170px 0;
}

li#nav_compania a:hover {
background-position: -1430px 0;
}