Ah, cool. I wasn't sure what "here" could possibly mean when we're talking about a language that was part of the web standard.
AFAIK, CSS syntax is inspired by the syntax of STTS, and STTS intentionally didn't use XML because it's a pain in the ass to hand-write and hand-read. I cannot argue with that assessment.
So CSS's syntax was based on an existing syntax, but it happened to be a syntax that didn't catch fire (which is so often the history of such things): it made plenty of sense at the time when the devs were looking at the options and maybe went "Well, we know XSLT and... It sucks and is hard to use, so what alternatives are there?" And STTS was apparently billed as an XSLT that human beings could write and read.
AFAIK, CSS syntax is inspired by the syntax of STTS, and STTS intentionally didn't use XML because it's a pain in the ass to hand-write and hand-read. I cannot argue with that assessment.
So CSS's syntax was based on an existing syntax, but it happened to be a syntax that didn't catch fire (which is so often the history of such things): it made plenty of sense at the time when the devs were looking at the options and maybe went "Well, we know XSLT and... It sucks and is hard to use, so what alternatives are there?" And STTS was apparently billed as an XSLT that human beings could write and read.