var viewportWidth;
  var viewportHeight;
    
  function getScreenWidth() {
    isNetscape = (navigator.appName == "Netscape");
    available = (isNetscape) ? window.innerWidth : screen.availWidth;
    return available;
  }
  
  function getScreenHeight() {
    isNetscape = (navigator.appName == "Netscape");
    available = (isNetscape) ? window.innerHeight : screen.availHeight;
    return available;
  }

  function setHeights() {
    bod = document.getElementById('body');
    mai = document.getElementById('main');
    con = document.getElementById('content');
    w = getScreenWidth();
    h = getScreenHeight();
    wo = (w - 1024) / 2;
    ho = (h - 770) / 2;
    
    bod.style.left = Math.abs(wo) + 'px';
    bod.style.top = Math.abs(ho) + 'px';
    //alert (con.offsetHeight);
    if (con.offsetHeight > 618) mai.style.height = (con.offsetHeight + 50) + 'px';
    else mai.style.height = 618 +  'px';
    viewportWidth = w;
    viewportHeight = h;
    
  }