Looks like the visual editor is the culprit. Since you are editing in visual editor mode, the editor is messing up the styling information in the code. See the below for an example of how the top slider that runs inside the iMac is getting messed up due to a div element being pushed to the top.
The slider on the top is running fine now that I corrected it.
Try to use the html editor for some of the pages with complex layouts and visual editor should serve you best when editing pages or blog posts with mostly textual content. Hope this helps.