Checkbox does not show up

Hi there,
I have installed this plugin on all my wp sites and it works great on most of them, but not on [ redundant link removed ]. It doesn’t show up in the comment section, but if you try to leave a comment, you get an error message saying to check the box. I’ve tried it in Chrome, Firefox and Safari, same result everywhere. I assume it is a conflict with the theme, but don’t know enough CSS to figure out how to get around it.

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