3 things I don’t know about from HIG
1. “if, after deciding on some audience characteristics, you end up with just a few app features, you’re on the right track: Great iOS apps have a laser focus on the task they help users accomplish.”
I thought one app dose it all was a good thing. Actually, no according to HIG.
2. Colors don’t have to be web safe.
3. Avoid CSS fixed positioning, so that content does not move offscreen when users zoom or pan the page.