function alertSize() {
  var myHeight = 0;
  if( typeof( window.innerWidth ) == 'number' ) {
    //Non-IE
    myHeight = window.innerHeight;
  } else if ( document.documentElement && ( document.documentElement.clientWidth || document.documentElement.clientHeight ) ) {
    //IE 6+ in 'standards compliant mode'
    myHeight = document.documentElement.clientHeight;
  } 

	if (window.innerHeight) {// Firefox
		yWithScroll = window.innerHeight + window.scrollMaxY;
	} else if (document.body.scrollHeight > document.body.offsetHeight){ // all but Explorer Mac
		yWithScroll = document.body.scrollHeight;
	} else { // works in Explorer 6 Strict, Mozilla (not FF) and Safari
		yWithScroll = document.body.offsetHeight;
  	}

  if ( yWithScroll <= myHeight ) {
		document.getElementById("container2").style.height = myHeight + "px";
	} 
}

window.onload=alertSize;