An anonymous reader writes: On 10 October 1994, Opera CTO Hakon Lie posted a proposal for Cascading HTML style sheets. Now, two decades on, CSS has become one of the modern web's most important building blocks. The Opera dev blog just posted an interview with Lie about how CSS came to be, and what he thinks of it now. He says that if these standards were not made, "the web would have become a giant fax machine where pictures of text would be passed along." He also talks about competing proposals around the same time period, and mentions his biggest mistake: not producing a test suite along with the CSS1 spec. He thinks this would have gotten the early browsers to support it more quickly and more accurately. Lie also thinks CSS has a strong future: "New ideas will come along, but they will extend CSS rather than replace it. I believe that the CSS code we write today will be readable by computers 500 years from now."