Tabs not aligned horizontally, rather vertically. How do I fix it?

This plugin doesn't render correctly. On some websites the "Click on a tab to select how you'd like to leave your comment" labels are stacked vertically. On other websites the tabs are horizontal. I want it horizontal on all my websites. How do I do that?

It looks right on this site http://www.conservatarianinc.org/2011/11/02/jesus-did-not-go-to-hell/
It looks weird on this site http://www.in-memory.org/darrin-christ/

I have dozens of sites. What's up?