Problem mit Navigation

/* Diese Klassen werden nicht angezeigt */
#extraDiv1 {display: none;}
#extraDiv2 {display: none;}
#extraDiv3 {display: none;}
#extraDiv4 {display: none;}
#extraDiv5 {display: none;}
#extraDiv6 {display: none;}
#pre_header {display: none;}
#post_header {display: none;}
#pre_content {display: none;}
div.header{display: none;}
h1#title{display: none;}

/* Gestalten der Links */
a:link {
color: Transparent;
font-size: 13px;
text-decoration: none;}

a:visited {
color: Transparent;
font-size: 13px;
text-decoration: none;}

a:hover {
color: Transparent;
font-size: 13px;
text-decoration: none;}

body {
background-color:#000000;}

*{ padding: 0; margin: 0; }

#Mein_Bild {
margin: 0 auto;
width: 980px;
height:500px;
background-image:url();}

#header_container {
position: absolute;
left: 50%;
margin-left:-490px;
top: +27px;
width: 980px;
height:104px;
background-color:#343434;
background-image:url(http://s11.directupload.net/images/090610/c7dfgx5x.png);
color:#FFFFFF;
font-size:13px;
border: 1px solid #FFFFFF;}

#content {
position: absolute;
left: 50%;
top: 140px;
margin-left:-320px;
width: 590px;
height: 500px;
padding:10px;
color: #F2F2F2;
font-size:13px;
background-color:#343434;
background-image:url();
border: 1px solid #FFFFFF;
overflow:auto;}

#sidebar_container{
position: absolute;
left: 50%;
top:140px;
margin-left: 300px;
width: 190px;
height: 400px;
background-color:#343434;
background-image:url;
border:1px solid #FFFFFF;
color:000000;
overflow:auto;}

nav_heading{
position: absolute;
left: 50%;
width: 160px;
height: 20px;
top:135;
margin-left: -490px;
color:000000;
background-image:url;
background-color:#343434;}

#nav_container{
position: absolute;
left: 50%;
top:170px;
margin-left: -490px;
width: 160px;
border:1px solid #FFFFFF;}

ul#nav{
width: 130px;
padding: 0px;
margin: 0px;}

li.nav_element{
list-style-type: none;
position: relative;
padding:5px;
width: 115px;}

li.nav_element a{
display: block;
width: 115px;
padding:4px;
font-weight: bold;
text-decoration: none;
text-align: left;
color:#F2F2F2;
background-color:#343434;
background-image:url(HIER BUTTON-ULR_1);
border: 2px solid #000000;}

li.nav_element a:hover{
color: #000000;
background-color:#C9C9C9;
background-image:url(HIER BUTTON-URL_2);}


table.rb_neu{
position:absolute;
left: 50%;
top:9px;
margin-left:-400px;}

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