It looks like there was DSSSL, which was designed to work with any SGML document, including HTML 3.2 documents. Curiously, the syntax was all written in s-expressions! [0] has some working links to materials on it.
Though it appears to have required an external processor, rather than being an alternative to "text/css" handled by the user agent. For that, you'd want to look elsewhere on Wikipedia's list [1]; one partial candidate is JSSS (JavaScript Style Sheets) in Netscape Communicator, which were JavaScript snippets that could actually be placed in <style type="text/javascript"> tags.
Though it appears to have required an external processor, rather than being an alternative to "text/css" handled by the user agent. For that, you'd want to look elsewhere on Wikipedia's list [1]; one partial candidate is JSSS (JavaScript Style Sheets) in Netscape Communicator, which were JavaScript snippets that could actually be placed in <style type="text/javascript"> tags.
[0] http://xml.coverpages.org/dsssl.html
[1] https://en.wikipedia.org/wiki/List_of_style_sheet_languages