Whatever it was built for, it doesn't run in Safari. And “but it runs in browser X” is almost as acceptable a retort as “it would run with square wheels”, in 2015, on the front page of HN.
Which goes to show that with a floor in the right shape, almost anything is possible :)
By the way, thank you for your colorful simile--it really spurred me to fix this issue this morning, and I've definitely learned to take cross-browser compatibility more seriously. Cheers.
Glad you took it this way, I'll have another look :)
I'm not sure if it's the only problem, but main.css contains a C-style "//" single-line comment. This is not valid CSS syntax.