I'm starting to see sites which work in Chrome but not Firefox - and not because of fancy web standards Firefox hasn't caught up with, but web page bugs showing the developers haven't bothered testing in other browsers.
I see this a lot and it's clear that most designers are building for Chrome and that they trust Firefox to render everything the same as Chrome will. The assumption that following the standards ensures a page will render the same in at least Chrome and Firefox has started to feel safe. That's a big improvement from the era that preceded, when you knew with certainty that cross-browser issues would exist. But it's not a completely safe assumption yet and may never be. Always test.
> 2014-12-15 08:00 PM
For example, but firefox needed the RFC3339 format.