Fix display corruption on IE

My recent submission (#223) resulted in a corrupt display on Internet explorer when displaying a story which was selected from the main menu. It was caused by having to set an explicit (and overly long) height on the "#separator:after" element which seems to confuse IEs positioning calculation when a hash is present on the URL. Setting overflow:hidden on the #separator element fixes it. 

![screenshot](https://cloud.githubusercontent.com/assets/104515/4009491/29b05b94-29e5-11e4-8e08-e3ef00ca4872.jpg)