I see what you mean, I've just started using Safari myself, and have something similar happening to me, possibly not exact because I'm on a PC, but when I preview a post, instead of one line at a time, it shows my whole post on one line, and cuts off the bottom. Not exactly an easy way to check your post. It may be a compatibility issue, however my specialty in computing lies in creating programs, not the internet, so I can't be sure.