WordPress Classic 1.5 Comment Field

Hello,

For some reason when a user starts typing in a comment field, the field expands across the full length of the browser window. It’s only apparent when you start typing in the field. This is a problem because it extends behind the sidebar making it impossible to see what’s being typed. I was trying to fix the width of the comments field, but haven’t had any success.

http://nutnation.com/NFL/Raiders/?p=208#respond

Any recommendations would be appreciated.
Thanks!