Scroll bar resizing

When this plug-in is activated on my site, the scroll bar on the right keeps changing size. I think it is because the footer keeps resizing to give the leaves a certain amount of room to “fall.”
I tried to add the following CSS:

body{
overflow-y:hidden;
}

but that made the scroll bar disappear completely, and I need to be able to see the rest of the page. Is there a way to fix this?

Otherwise I really love this plug-in!
Thanks.

The page I need help with: [log in to see the link]