function viewport() {

var elem = (document.compatMode === "CSS1Compat") ? 
    document.documentElement :
    document.body;

var height = elem.clientHeight;
var width = elem.clientWidth;
if(height < 570) {
  document.getElementById('container').style.marginTop = 0;
  document.getElementById('container').style.top = 0;
  }
}