first post - forgive errors. I have been struggling with why my sticky submenus were not 'sticking'. I always build simple templates for behaviour before I add them to a template so I knew all my css was fine.
It turned out that the css from the slider plugin had an overflow:hidden applied to html - and that will block any sticky behaviour. The slider plugin was in there because I was building on an inheritance of antimatter. I thought I'd post this because it drove me up the wall but was a simple fix once I'd found it.