Css - height 100% need help plz

body {
 margin:20px;
 background:#808080;
 color: #333333;
 text-align:center;
 padding:0;
 }

a:link {color: #FF9900; text-decoration: none}     /* unvisited link */
a:visited {color: #FF9900; text-decoration: none}  /* visited link */
a:hover {color: gray; text-decoration: none}   /* mouse over link */
a:active {color: #FF9900; text-decoration: none}   /* selected link */

#outer {
 text-align:left;
 border:1px solid #000000;
 width:100%;
 margin:auto;
 }

#hdr {
 height:100%;
 background:#eeeeee;
 color: #333333;
 }

#bar {
 height:0px;
 background:#c0c0c0;
 color: #333333;
 border:solid #000000;	
 border-width:1px 0 1px 0;
 }

#bodyblock {
 position:relative;
 background: #dcdcdc;
 color: #333333;
 width:100%;
 padding:0;
 }

#l-col {
 float:left;
 background:#dcdcdc;
 color: #333333;
 width:19%;
 height:auto;
 }

#cont {
 width:80%;
 height:auto;
 background:#ffffff;
 color: #333333;
 border:solid #000000;	
 border-width:0 0 0 1px;
 text-align:left;
 }

#ftr {
 height:100%;
 background:#c0c0c0;
 color: #333333;
 border:solid black;
 border-width:1px 0 0 0;
 margin:0;
 }