Firefox and IE dont calculate body.scrollTop correctly

[Duskfall]

Though in codepen demo works, in my case the firefox 41.0.1 and IE 11 dont calculate the body scroll correctly returning 0 instead of 1000+
This doesn't happen in Chrome.
I fixed this for me changing the line to :

left = posX - rect.left - ripple.offsetWidth / 2 - window.pageXOffset;
top = posY - rect.top - ripple.offsetHeight / 2 - window.pageYOffset;

[Creativenauts]

You sure your not zoomed in?

[sztrzask]

I can confirm this happening on FF.

[LukaszWatroba]

On OsX and Firefox 44.0.2 everything seems to be working fine even if I zoom in.