I am using margin: 0 auto; and display: block; to make images sit in the center of a div. It works perfectly fine in all browsers except Firefox, which is pushing the image all the way to the right, outside of the div.

You can see the error happening live here: http://theme.pippinsdesign.com/css/blog-post-3/

What is supposed to be happening is the image, with class="aligncenter", should be centered in the div with the class="entry", which has a width of 490px.