function resizeMiddle() {
	
  var innerHeight = window.innerHeight || (window.document.documentElement.clientHeight || window.document.body.clientHeight);
  var newHeight = 0;
  if(innerHeight<500)
    newHeight = 500;
  else
    newHeight = innerHeight-431;
	browserVer = navigator.appVersion;
	
	if(browserVer.indexOf("MSIE 6.0") != -1)
	  document.getElementById('main').style.height = newHeight + "px";
  else
	  document.getElementById('main').style.minHeight = newHeight + "px";
} 

window.onload = resizeMiddle;
window.onresize = resizeMiddle;