comment box width

I was looking on here not long ago for how to fix the comment box width issue, where it stretches out the width of the screen. Among the discussions was a link to someone’s web page (404 something) that had a great explanation of how it worked and exactly how to fix it (for those of us not so incredibly talented).
Does anyone know where that posting ended up? The link there now doesn’t find anything.
Thanks.
Jon in Michigan
http://completerunning.com/chocolate-runners-blog/