Comments Plus Tabs don't appear in Google Chrome

Okay - I'm assuming this is some kind of CSS conflict issue with the main stylesheet, but I just can't seem to pin it down.

For comments at Comments Plus is working great for me in Firefox and IE. However, in Chrome, the tabs don't show up at all.

I've tried tweaking CSS, but can't put my finger on the issue.

Would be obliged to anyone able to show me the error of my ways!