Auto align images in posts
 

I asked this a while back and got Lynne a little confused as to what I was wanting to do.
Here's the Readers Digest version of what that was about.
I asked if it was possible to have VB center align images that didn't completely fill out the width of the post. General consensus was it's not possible. Uh huh...
I found 2 css entries in postbit.css that do have a direct affect on how the content is displayed.
If you add text-align: center; to the one above, it center aligns everything. Text and images. Not really the desired result
That same text-align is totally ignored when used in the second code block. However if a margin-left with a value is put in place, it pushes the image over however many pixels you put in and does not bother any text posts.
So now a little progress has been made in the right direction as in finding what controls the images in posts. Now my question is what would be the correct instruction and its syntax to make the second code block center images all by itself?
Reason being I may post a small image that doesn't get resized but still needs to be centered up in the post. BTW in the posts with images there will be no text.