Thanks for flagging this for us. Can't replicate the error at the moment, but will take jQueryIsAwesome's advice. Meantime, if you get a sec please send a screenshot?

You can actually test this kind of bug in Chrome; just make the width of the window little and then scroll horizontally.

The "position:fixed" breaks many things on mobile, is always better to avoid it or at least change it when the user is from a smartphone.