Hakon Wium Lie is best known as the person who proposed Cascading Style Sheets. On his own page at the World Wide Web Consortium he writes, “In 1994 I proposed the concept of Cascading Style Sheets which are now, some years later, implemented by major browsers.” That proposal grew into the dominant way the web is styled.
At the time, Lie was working alongside Tim Berners-Lee, the inventor of the web. His page describes the arrangement plainly: “I work for the guy who invented the Web. His name is Tim. He’s now the director of the World Wide Web Consortium.” Lie was based at INRIA in France and, by his own account, spent most of his time “developing and promoting style sheets.”
His original document, “Cascading HTML Style Sheets — A Proposal,” is dated 10 Oct 1994 and signed “Hakon W Lie (howcome@info.cern.ch),” tying him directly to CERN, the birthplace of the web. The idea it described, letting multiple style sources cascade together with weighted influence shared between author and reader, became the core of the eventual standard.
Lie went on to co-edit the CSS specification. The CSS level 1 W3C Recommendation, published 17 Dec 1996, carries his work forward into the formal standard that browsers implement. He later served as chief technology officer of the Opera browser company, continuing to push for open web standards.