I have modified the content to fix the issue. You may need to change the first slide of the slider to make the image have a bigger height (need to maintain the aspect ratio so that the image fits the imac) but all other slides look good. Basically when you modified the content in the Visual tab, WordPress messed up the layout which made the slider to not function right. You should be fine now. Pls save the change the changes made from the HTML tab and preserve it for later use in case WordPress visual editor auto formats the post again breaking he layout. Thanks