Fixing a small problem with a theme

I am having problems with the table structure in my slightly modified Sky theme; however, it exists in the original as well.

If you notice on the Sky Theme demo page:
http://sky.modernwebservices.com/node/1

and on my page:
http://www.seriousweightloss.net/epworth-sleepiness-scale

The tables extend off the right hand edge of the page. Unlike most tables that limit the cells to just slightly larger than the largest text input within that column, these tables seem to divide the column width into equal parts regardless of browsre resolution (i.e. it evenly splits whatever width is available between left sidebar and right hand page edge by however many columns.

This problem occurs in IE7, Opera, Safari. In FireFox, the tables do generate a right hand edge, but they still use all available space regardless of width of actual data in the column heading or data.

Any thoughts on how to resolve this?

Thanks in advance :)