I haven't checked deep in your code yet but it looks like you are relying on the default margins for your h2 title. IE doesn't apply top margins by default but all other browsers do.
This will apply to other elements such as all headings,p,ol,ul etc.
IE just applies a bottom margin and most browsers apply a top and bottom margin by default. Note that the margin amounts vary wildly by browser so you should set them explicitly to your needs.