No longer supports IE 6/7, Firefox < 4, and Safari < 5.
* Make use of `inherit` to simplify some of the rules.
* Remove a lot of padding and margin normalization, particularly for
typographic elements, because modern browsers share common base
styles.
* Add `quotes` normalization. While all target browsers support
`quotes`, they don't share a common set of quote styles. Opera and IE
use "curly" quotes whereas other browsers do not. Browsers don't
appear to set different quotes depending on the language (via the
`lang` attribute) of the content.
* Remove all list normalizations and they aren't needed anymore.
* Remove a handful of form normalizations that targetted IE 6/7 or
Firefox 3.
