display a complete node
It's a bit strange that node_view is not returning a fully formatted node. The node module calls node_view inside it's own hook_menu to handle node/%nid requests.

Is there any chance that your CSS is selecting on something specific to node/%nid pages or your templates are setup in a non-standard way. 

Can you show us the exact HTML string that is being returned by that function and the HTML string you are expecting?