function showBox(){
    $('overlay').show();
    $('box').show();
    center('box');
    return false;
}

function hideBox(){
    $('box').hide();
    $('overlay').hide();
    return false;
}

function center(element){
   
    try{
        element = $(element);
    }catch(e){
        return;
    }

    var my_width  = 0;
    var my_height = 0;

    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';
}