normal kubrick style should be alright in most cases; in this case there was an additional class .mceTemp in the way.
general, the best help you can give is to post a link to your live site, which you have done right from the start, great.
with webtools (the free firefox and its free web developer add-on for instance), it is then easy to see what theme you are using, and all the style.css, and the html from the browser.
only if you would need help with template files (php files) would you need to provide copies of these files.
if you could try the suggested fix, hope it works.
edit style.css from your theme (you can do this probably in 'admin' 'appearance' 'editor' )
and scroll down in style.css virtually to the end, until you see other lines with .wp-caption - and the you will see
/* End captions */
add the suggested lines just before that.
(in general, it does not really matter where you add the new lines, as they are quite specific to the alignment of images with captions. but with new styles, it is often the best idea to add them at the end of the style.css.)