I just got this fantastic tip from Jamie Boyd , a colleague of mine:
The :first-child and :last-child selectors are super-useful for applying alternate styling to items in lists and things like that (e.g. removing the margin from the last item in a container-spanning nav bar). But when it comes to browser support, they are not equal.
:last-child is actually only supported in IE9+, whereas :first-child has had partial support since IE7 (where it works, but styles won?t update if dynamic content is added).
So if you can, use :first-child rather than :last-child.