Transparencia em Menu

Olá pessoal, estou fazendo um menu e gostaria que eles ficasse com fundo transparente. como faço?www.famec.edu.bro script eh esse pessoal:<style type="text/css">.mh { background-color : #0564b8; color : #ffffff; display : block; font-family : Verdana, Geneva, Arial, Helvetica, sans-serif; font-size : 12px; font-weight : bold; padding : 1px 5px 2px 4px; vertical-align : center; width : expression("100%"); text-align: center;}.mn { background : #0564b8; padding : 1px; position : absolute; z-index : 100; border: 1px ; text-align: center;}.mn a{ border : 1px #0564b8 solid; color : #ffffff; display : block; font-family : Verdana, Geneva, Arial, Helvetica, sans-serif; font-size : 12px; padding : 1px 5px 2px 4px; text-decoration : none; vertical-align : center; width : expression("100%"); font-weight : normal; text-align: center;}.mn a:hover { background : #0c436e; text-decoration : none; color : #ffffff; text-align: center; font-family: Verdana, Arial, Helvetica, sans-serif; font-size: 12px; }.sp { border-bottom : #0564b8 1px solid; border-top : #0564b8 0px solid; margin : 2px 2px; text-align: center;} #divUpControl{position:absolute; width:320; left:10; top:10; z-index:1; text-align:center} #divDownControl{position:absolute; width:320; left:10; top:270; z-index:1; text-align:center} #divContainer{position:absolute; width:320; height:240; overflow:hidden; top:30; left:10; clip:rect(0,320,240,0); visibility:hidden} #divContent{position:absolute; top:0; left:0} </style>o que faço, pra deixá-lo transparente?bjos