text-transform property is a tricky one. At first sight, it looks easy: uppercase, lowercase and capitalize. But capitalization varies from one language to another, and
text-transform, per CSS3 Text, must take this into account.
The Dutch language has a digraph: ij. This is not really a separate letter (and almost never in computerized text). But both components of the digraph are always capitalized together:
ijsland → IJsland
This is specific to the Dutch language, which is defined in the HTML document by using the HTML
lang or XHTML
xml:lang attributes with the nl language code. It landed today in Firefox Nightly, and will be in Firefox 14.