Where can I adjust the showthread width?

[carwash]

For some reason all of the threads on my site are narrower than the things above them like the navbar. Where can I adjust the width of the showthread page to make it match up?

I have attached a screenshot so you can see what I'm talking about.

[Dismounted]

Edit the showthread template.

[Princeton]

try..
remove $spacer_open and $spacer_close in showthread

[Hicksatpd]

I am looking to do this too, and there are multiple instances of $spacer_open and $spacer_close which ones should I be removing?