body {
margin:0;
padding:0;
height:100%; /* this is the key! */
}
#header {
height: 50px;
background-color: #EAEAEA;
border:1px solid #333;
padding:4px;
}
#left {
position:absolute;
left:0;
top:80px;
padding:0;
width:200px;
height:60%; /* works only if parent container is assigned a height value */
color:#333;
background:#eaeaea;
border:1px solid #333;
}