function showBox(){
 Element.show('overlay2');
 center('box');
 return false;
}

function hideBox(){
 Element.hide('box');
 Element.hide('overlay2');
 return false;
}

function center(element){
 try{
 element = document.getElementById(element);
 }catch(e){
 return;
 }

 var my_width = 100;
 var my_height = 20;

 if ( typeof( window.innerWidth ) == 'number' ){
 my_width = window.innerWidth;
 my_height = window.innerHeight;
 }else if ( document.documentElement &&
 ( document.documentElement.clientWidth || document.documentElement.clientHeight ) ){
 my_width = document.documentElement.clientWidth;
 my_height = document.documentElement.clientHeight;
 }
 else if ( document.body && ( document.body.clientWidth || document.body.clientHeight ) ){
 my_width = document.body.clientWidth;
 my_height = document.body.clientHeight;
 }

 element.style.position = 'absolute';
 element.style.zIndex = 99;

 var scrollY = 0;

 if ( document.documentElement && document.documentElement.scrollTop ){
 scrollY = document.documentElement.scrollTop;
 }else if ( document.body && document.body.scrollTop ){
 scrollY = document.body.scrollTop;
 }else if ( window.pageYOffset ){
 scrollY = window.pageYOffset;
 }else if ( window.scrollY ){
 scrollY = window.scrollY;
 }

 var elementDimensions = Element.getDimensions(element);

 var setX = ( my_width - elementDimensions.width ) / 2;
 var setY = ( my_height - elementDimensions.height ) / 2 + scrollY;

 setX = ( setX < 0 ) ? 0 : setX;
 setY = ( setY < 0 ) ? 0 : setY;

 element.style.left = setX + "px";
 element.style.top = setY + "px";

 element.style.display = 'block';
}