jQuery/quicksand/css problem in IE/Firefox (but not chrome)

I'm trying to create an icon-swapping effect with jQuery+quicksand. It works swimmingly on Chrome, but on IE and Firefox, the effect doesn't work properly. Since the far-more-complicated quicksand demos all work fine in all browsers I assume I'm doing something stupid with CSS.

Site is here: http://outsharked.com/test

When the icons animate, they stack up like a vertical list on FF and IE, whereas they should just rearrange horizontally, as they do in Chrome.

Any help would be appreciated. Containing div height is fixed; the styles for the UL are basic (and almost nonexistent in the quicksand demos) so I am not sure what could be the pro开发者_如何学Goblem. It's almost as if it thinks the list is supposed to be a vertically-arranged list on the animation, but no such style is ever assigned as far as I can tell.

If you give your Div a fixed width, it works in Firefox.