function resize(){
var sidebar = document.getElementById("sidebar");
var main = document.getElementById("main");

var sidebarH = document.getElementById("sidebar").offsetHeight;
var mainH = document.getElementById('main').offsetHeight;

var maxH = mainH;

maxH = Math.max(sidebarH, mainH);

sidebar.style.height = maxH+'px';
main.style.height = maxH+'px';
}