var theHeight;
if (window.innerHeight) {
	theHeight = window.innerHeight
} else if (document.documentElement && document.documentElement.clientHeight) {
	theHeight = document.documentElement.clientHeight
} else if (document.body) {
	theHeight = document.body.clientHeight
}
function centraliza(){
	var el = document.getElementById("geral");
	var topo 	= (theHeight - 590) / 2;
	if (topo > 0) el.style.marginTop = topo + 'px';
}

function checkHeight(){
var id = 'geral';
var theHeight = 0;
   if (window.innerHeight) {
		theHeight = window.innerHeight
   } else if (document.documentElement && document.documentElement.clientHeight) {
		theHeight = document.documentElement.clientHeight
   } else if (document.body) {
		theHeight = document.body.clientHeight
   }

  var el = document.getElementById(id);
  var elHeight = el.clientHeight;
  var diff = theHeight - elHeight;
  if (diff > 0){
    el.style.marginTop = (diff / 2) + 'px';
  }
}