function getDocHeight() {
  var winHeight;
  var d = document;
  if (typeof window.innerWidth!='undefined') {
    winHeight = window.innerHeight;
  } else if (d.documentElement && typeof d.documentElement.clientWidth!='undefined' && d.documentElement.clientWidth!=0) {
    winHeight = d.documentElement.clientHeight;
  } else if (d.body && typeof d.body.clientWidth!='undefined') {
    winHeight = d.body.clientHeight;
  }
  return winHeight;
}

function setDocHeight() {
  var elements = getElementsByClassName("main");
  var doc_height = getDocHeight();
  doc_height = doc_height - 90;

  for(i=0; i < elements.length; i++){
    elements[i].style.height = doc_height + 'px';
  }

  var main_first = getElementsByClassName("main_first");
  var main_first_height = getDocHeight();
  main_first_height = main_first_height - 150;
  
  for(i=0; i < elements.length; i++){
    main_first[i].style.height = main_first_height + 'px';
  }
}