I'm in the process of implementing Responsive Design on my wife's business's website, and I'm trying to decide how to handle the horizontal nav menu with drop-down items.

Is there a "best practices" way of handling this? One thought I had (and which I used to swap footers) was to have two separate HTML versions, and use #display: none; in the regular stylesheet to hide the mobile footer, and vice versa.

How do you guys handle drop-down menus for mobile devices?