In 2.0.18a (and before), the output after adding to cart of the modal window comes out like this:
<a class="continue" href="/my-products">Continue Shopping</a>
<a class="showcart floatright" href="/my-cart">Show Cart</a>
<div>The product was added to your cart.</div>
<h4>Premium Widget was added to your cart.</h4>
The opening div tag needs a class in order to facilitate styling. The message div could use a class as well. For my template, I styled a.continue to float left, but I don't have any way to style the message div, so "The product was" appears before the links and without the float left, it does not look right either.
The only way to style it right now is to edit a core VM file, or style the first div after all modal windows using fancybox.