lucy24 - 1:20 am on Dec 20, 2012 (gmt 0)
Do you ever read the html or css forums? There's a standard bit of advice that fits in really well here.
Are the three selectively-visible divs all in the same place? Can more than one be visible at the same time?
Are the two lower parts of the map intended to overlap by one px or was that a typo?
Oh, and it never hurts to stop by caniuse dot com and make sure everything you've got is supported.