function vertalign()
{
    var lmt = document.getElementById('centrage');
    var container = document.documentElement;

    if(lmt && container) {
        var containerHeight;
        if (container.innerWidth) {
            containerHeight = container.innerHeight;
        }
        else {
            containerHeight = container.clientHeight;
        }
        var lmtHeight;
        if (lmt.innerWidth) {
            lmtHeight = lmt.innerHeight;
        }
        else {
            lmtHeight = lmt.offsetHeight;
        }
        var y = Math.ceil((containerHeight - lmtHeight) / 2);
        if(y < 0) {
            y = 0;
        }
        lmt.style.position = "relative";
        lmt.style.top = y + "px";
    }
    if (document.getElementById) {
        document.body.style.visibility = 'visible';
    }
}

function addevent(obj,evt,fn,capt)
{
    if(obj.addEventListener) {
        obj.addEventListener(evt, fn, capt);
        return true;
    }
    else if(obj.attachEvent) {
        obj.attachEvent('on'+evt, fn);
        return true;
    }
    else
        return false;
}

if (document.getElementById && document.getElementsByTagName) {
    addevent(window, 'load', vertalign, false);
    addevent(window, 'resize', vertalign, false);
}