Error correction: Date of quote was 1994. #CSS in terms of a separation of style actually emerged out of Tim Berners-Lee's NeXT browser/editor. He included but did not publish a simple style sheet (First USER style FTW! hehe). Håkon Wium Lie who, while at CERN realized the need.

The separation of document and style had a working corrolarry at the time: Desktop Publishing. Master style sheets anyone? #CSS Another irony is 1994 is not just the idea of style sheets but the year the W3C was formed! The CSS-WG? 1996. First major implementation? IE3.

FWIW, the concept of styles is older; Framemaker, for example, worked heavily with styles, in the 1980s already. You could do otherwise, but it was your fault to do so.