window.onload = function() {
    AddHeight();
}

function AddHeight() {

    // Get Content Vars
    var ContentHeight = document.getElementById("maincontent").offsetHeight;
    var HeaderHeight = document.getElementById("Header").offsetHeight;
    var FooterHeight = document.getElementById("FooterBar").offsetHeight;
    var AdaHeight = document.getElementById("ada_footnote").offsetHeight;

    // Get Nav Vars
    var NavHeight = document.getElementById("Navigation").offsetHeight;
    var NavBtm = document.getElementById("NavBottom");
    var NavBtmHeight = NavBtm.offsetHeight;

    var Diff = ContentHeight - HeaderHeight - FooterHeight - AdaHeight;

    if (NavHeight != ContentHeight) {
        NavBtm.style.height = Diff - NavHeight + NavBtmHeight + "px";
	}

}