DatePicker - Prev and Next Links are Unreadable?

I'm encountering some anomalies with DatePicker, and a theme I created
using Themeroller. Specifically, the Prev and Next links look
garbled.
An online demo is here:
http://www.flavorzoom.com/datepicker_anomaly/datepicker_anomaly.html
How can I correct this?
Thanks in advance to all for any thoughts.
-Vik