"How much of this stuff will doom you if any of your users are still stuck on IE?" Or "stuck" on Firefox. His nice minimal html running example works on Chromi

"How much of this stuff will doom you if any of your users are still stuck on IE?" Or "stuck" on Firefox. His nice minimal html running example works on Chromium/Ubuntu for me, but not on FF8/Ubuntu for me. In the part where you're supposed to see the html inside the pre tag, all I get rendered is "undefined", although I do get the three emphasized bangs at the end of "Foundation." Is this all "nice if you're on Chrom(ium)", or am I likely doing it wrong?