function calcColumns(){
    var center = document.getElementById('centerColumn');
    var right = document.getElementById('rightColumn');
    var middle = document.getElementById('middleWrap');

    var centerHeight = center.offsetHeight;
    var rightHeight = right.offsetHeight;

    if(centerHeight > rightHeight){
        middle.style.height = parseInt(centerHeight - 100) + 'px';
    }else{
        middle.style.height = parseInt(rightHeight - 100) + 'px';
    }
}