// sets the height of the left sidebar to that of the main body if necessary
if (document.getElementById('body_main').offsetHeight > document.getElementById('body_sidebar').offsetHeight) {
    var divB = document.getElementById('body_main').offsetHeight - 52;
    document.getElementById('body_sidebar').style.height = divB + 'px';
}
else {
    var divB = document.getElementById('body_sidebar').offsetHeight;
    document.getElementById('body_main').style.height = divB + 'px';
}