function setNav() {
    var colLength;
    var offSet;
    var leftNavLength;

    leftNavLength = document.getElementById("left_navigation").offsetHeight;
    colLength = document.getElementById("content_body").offsetHeight;
    offSet = 85;
    colLength = colLength + offSet;
    
    if (leftNavLength > colLength)
        colLength = leftNavLength;
    
    document.getElementById("left_nav_middle").style.height = colLength + "px";  
}