XSLT is the transformation part of XSL (hence the T), meant for transforming XML into other formats, including things like XSL-FO which is the formatting part of XSL. As it is a general purpose language (with iteration, recursion and conditionals) it's not that surprising that it is Turing-equivalent.

XSL-FO is the formatting part of XSL (i.e. the bit most like CSS) - I'd be pretty surprised if this was shown to be Turing-equivalent.