Corner field in task board card is not drawn properly in FF3 or Safari on Mac

The 1st screenshot shows that the assignee (which is my corner field) paints below the card instead of on the card. This is identical in FF3 or Safari. The summary card shows the corner field fine (the 2nd screenshot)

This is a problem because it becomes non-intuitive to change the assignee field since it can only be done on the large card via ajax.