Reduce Comment box width – Cuts off some user names

I want to reduce the width of the comment box. Not the box a user types their comments into, the box that displays that displays their comment once the comment is entered. Some users with longer names have the end of their names cut off when their comment is shown, as the box displaying their comment covers it. I tried, but was unsuccesful in discovering how this could be changed. Any help pointing me in the right direction would be appreciated.

My comment page: https://3widealley.com/wordpressblog/?p=313&cpage=44#comments