How to customize the "Added to Cart" popup window

Hi,

I would like to increase the height of the "Product successfully added to the cart" popup window. I have an extension on one of my sites that displays a live chat box at the bottom of every page on the site. It also displays in the "Product successfully added to the cart" popup window, which is fine, but it covers much of the information in the window. I want to make the window taller so that the live chat box displays lower in the window and the information can be read easily. Is there an easy way to increase the height of the popup window?

Thanks,
Chi=ris

Worked perfect.

Thank you!