I've created a custom template (based on classic) to match our existing site. I'd be happy to share a link if it will help but I'm pretty sure I've narrowed down my problem.
When I attach an image and apply a caption to it, the div for the caption seems to add a 10px margin which throws off the entire layout.
My column width is 380, and the attached image itself is 380. The div for the caption that surrounds the image has a style attribute that has a width of 390. Now I cannot figure out where this number 390 is coming from. Here's the source code I'm getting
<div id="attachment_28" class="wp-caption alignnone" style="width: 390px"><img class="size-medium wp-image-28" title="anilox_400" src="http://www.midstatelitho.net/articles/wp-content/uploads/2008/11/anilox_400-300x240.jpg" alt="Anilox Roller Cells Magnified at 400x" width="380" height="321" /><p class="wp-caption-text">Anilox Roller Cells Magnified at 400x</p></div>
I've searched high and low through my source and can't seem to find it. It seems strange that the number 390 would be written into the template code so I assume there's a calculation somewhere in the caption code that is coming up with 390.