Each browser accepts different CSS and also applies their own styling to different HTML elements. You'll
never have all 3 looking the same. There used to be little "tricks" to make CSS specific to IE, but am not aware of any that are specific to IE9 without causing your site to fail CSS validation (not a big deal if you don't care about W3C) otherwise you can try the below search.
lmgtfy.com/?q=IE9+only+css