menus displaying behind the masthead

Hi, please see URL: http://testing.backstageweb.net/. Mouse over nav link "Page 1" and you'll see that the menus are displaying behind the masthead; I don't know why. Relevant code:

.menu#nav-primary {
background:url(../images/navbar_bkgrnd.jpg) repeat-x;
overflow:hidden;
width:1050px;
height:62px;
margin:0;
z-index:500;
position:relative;
}

#masthead {
background:#FFF;
overflow:hidden;
}

I may be looking at the wrong code (probably am) but I appreciate any help.

Thanks.

john

Remove overflow;hidden; from #nav-primary.menu

Thanks! : )