In Firefox, there’s been a problem with horizontal and vertical spacing around post images. In IE, illustrations in posts generally look okay. In Firefox, the text appears to butt up against the image.

Here’s the solution that I’m using with WordPress 2.3, thanks to the WordPress Support forum:

I’ve added something like this to my style.css in my theme folder:

img {padding:5px;}

That puts five pixels of space around all four sides of the image. You can increase or decrease that, according to your tastes.

If you want to specify different padding on different sides, you’ll need to do something more like this:

img {padding:5px 10px 5px 10 px;}

(Tip:  I’m pretty sure that the border code goes clockwise around the image, starting at the top of the clock.  My CSS expertise isn’t red-hot, so I may be wrong about that, but… well, it’s worth a try, right?)

Also, if you’re seeing a border around your post illustrations in Firefox, edit the image in the post.  Be sure that WordPress didn’t add a border.  I’m not sure if it was my own typo or a WordPress auto-fix, but changing the image details (in the popup window at the Write Post panel), to border=0 , solved it.