[Plugin: Facebook Comments] Changing the width of comment box

I’m not sure if you have figured this out or not, but if you haven’t then here goes: click on settings > facebook comments. Scroll down to the settings area and change the width where I have indicated.

I have the same question but I have a responsive design so I don’t want to set a static width. When the screen is small, the comments rearrange themselves on top of the sidebar as seen here. First question, is this possible? And if yes, where do I do that? Thanks!