function chsize(){

  el = document.getElementById('div_rsz');
  if(document.body.clientWidth>1200){
el.style.left = '50%';
el.style.margin = '0 0 0 -600px';
el.style.width = '1200px';
el.style.position = "absolute";
  }else if(document.body.clientWidth<1024){
el.style.left = '';
el.style.margin = '0';
el.style.width = '1024px';
el.style.position = "relative";
  }else{
el.style.width = '';
el.style.left = '';
el.style.margin = '0';
el.style.position = "relative";
  }

}