I've just installed WP and am using the default unmodified Twenty Thirteen theme.
In one post I have an image with the alignment set to right. It displays well in the visual editor but it is not correctly aligned (on the right) with the text in the preview or live post. See here (blog.linkody.com/seo/using-linkody-to-monitor-anchor-text-and-avoid-google-penalties)
What's the problem?