In IE8 or less, the sidebar (when set to three colomns) is shifted to the bottom of the page rather than the side. I made a work around by changing the the css of #secondary to 225px rather than 260px but I’m not sure if that’s the best solution.
Also in IE 8 or less, the dropdown menu on the home page goes behind the slider so you can’t see all the options, and if you move your mouse to hover the dropdown menu it disappears. This can be seen on the Leaf demo page too. I’ve tried putting the z-index up on a bunch of menu variables but haven’t been successful.