Problema con menú

[luisgzafra]

Buenas,

Estoy preparando un menú desplegable pero me encontré con un error:

Tengo la siguiente css:

Código CSS:

#headbox a {
color: #11C;
text-decoration: none;
}
 
#headbox{
background-color: #2D2D2D;
border-bottom: 1px solid black;
font-size: 24px;
height: 29px;
opacity: 1;
filter: alpha(opacity=100);
position: absolute;
top: 0;
width: 100%;
z-index: 0;
right: 0;
}
 
#cabecera{
background-image: -moz-linear-gradient(top, #416D99, #2C5687);
background-image: -webkit-gradient(linear, center top, center bottom, from(#416D99), to(#2C5687));
border-bottom: 2px solid #E5E5E5;
border-top:1px solid #4F84AF;
font-size: 24px;
height: 65px;
position: absolute;
width: 100%;
margin: 22px auto;
right: 0px;
left: 0px;
z-index: -1;
}
 
 
 
#headbox .gbtcb {
position: absolute;
visibility: hidden;
}
 
.gbtc, .gbmc, .gbmcc {
display: block;
list-style: none;
margin: 0;
padding: 0;
width: 235px;
}
 
.gbtc, .gbmc, .gbmcc {
list-style: none;
}
 
.gbt {
    position: relative;
    display: -moz-inline-box;
    display: inline-block;
    line-height: 27px;
    padding: 0 0 0 10px;
    vertical-align: top;
    background: #2D2D2D!important;
    visibility: visible;
}
 
.gbt42 {
background: white;
position: relative;
display: -moz-inline-box;
display: inline-block;
line-height: 27px;
padding: 0 0 0 10px;
vertical-align: top;
box-shadow: 0px 5px 10px #ccc;
-moz-box-shadow: 0px 5px 10px #ccc;
-webkit-box-shadow: 0px 5px 10px #ccc;
}
 
.gbzt, .gbgt {
cursor: pointer;
display: block;
text-decoration: none !important;
}
 
.gbts {
border-left: 1px solid transparent;
border-right: 1px solid transparent;
display: block;
padding: 1px 3px 0px 2px;
position: relative;
z-index: 1000;
font-size: 15px;
left: -7px;
}
 
 
 
 
 
#headbox .center {
margin: 0 auto;
width: 1045px;
height: 30px;
}
 
#headbox .gbtb2 {
display: block;
border-top: 2px solid transparent;
}
 
#gbz .gbzt, #gbz .gbgt,#gbz2 .gbzt, #gbz2 .gbgt, #gbg .gbgt {
color: #225985!important;
background: transparent;
}
 
#gbz ul.gbtc li.active {
border-top: 2px solid #DD4B39;
}
 
.gbzt-hvr, .gbzt:focus, .gbgt-hvr, .gbgt:focus {
background-color: #4C4C4C;
background-image: none;
background-position: 0 -102px;
background-repeat: repeat-x;
outline: none;
text-decoration: none !important;
}
 
#gbg6.gbgt-hvr,#gbg6.gbgt:focus
{background-color:transparent;background-image:none}
 
#gbg {
float: right;
position: relative;
padding-right: 5px;
}
 
#gbg ul li ul{
position: absolute;
border: 1px solid #C3D1EC;
box-shadow: 0 1px 5px #CCCCCC;
margin-top: -1px;
display: none;
padding: 0px 16px 0px 0;
}
 
.gbtsa {
padding-right: 9px;
}
 
 
.gbma {
position: relative;
top: -1px;
border-style: solid dashed dashed;
border-color: transparent;
border-top-color: silver;
display: -moz-inline-box;
display: inline-block;
font-size: 0;
height: 0;
line-height: 0;
width: 0;
border-width: 3px 3px 0;
padding-top: 1px;
left: 4px;
}
 
 
#headbox .nav_list {
color: #36C;
list-style: none;
top: -23px;
position: relative;
border: 1px solid #BEBEBE;
background: white;
-moz-box-shadow: 0px 3px 3px 0px #CCC;
-webkit-box-shadow: 0px 3px 3px 0px #CCC;
z-index: 2;
zoom: 1;
padding: 4px 0px;
left: -36px;
width: 230px;
}
#headbox .name_user {
color: black;
font-weight: bold;
font-size:small;
left:65px;
top: 7px;
position: relative;
color: #36C;
display: block;
}
#headbox .name_rango {
color: #5A5A5A;
display: block;
font-size: 13px;
left: 65px;
position: relative;
display: block;
}
 
#headbox .image_user {
display: block;
padding-left: 5px;
padding-top: 10px;
position: absolute;
}
 
.gbmtc {
padding: 0;
margin: 0;
line-height: 27px;
left: -10px;
position: relative;
}
.gbml1 {
display: inline-block;
margin: 0 15px;
padding: 0 10px;
}
 
.gbmh {
border-top: 1px solid #E5E5E5;
font-size: 0;
margin: 10px 0;
}
 
#gb {
font: 13px/27px Arial,sans-serif;
}
 
.gbmt, .gbml1, .gbmt:visited, .gbml1:visited {
color: #36C !important;
display:-webkit-box;
text-decoration: none !important;
font-size: small;
background: #FFF;
}
 
 
.gbmt:hover,.gbml1:hover {
background: #EFF3FB;
outline: none;
}
 

El problema es que con la div que tiene el contenido no se muestra el menú, se muestra por detrás del contenido y debería verse por delante.

Necesito poner una div que se vea sobre todas las demás.

No tengo mucha idea de diseño, es por eso que pregunto