If Preview mode looks significantly different than the same page uploaded to your server and viewed in Safari, then there is a very good chance that the upload didn't complete successfully. There are many reasons why this might happen, your network was interrupted, problems on your host, incorrect publishing settings, etc. The simplest way to remedy this is to choose Re-Publish All Files from the File menu. It takes a while, but it will get things back in sync.
- Note: Re-Publish All Files is not the same as regular Publish. You must manually choose that option from the menu. It forces a re-upload of everything instead of only uploading changes.