This kind of stuff is par for the course when developing for web iOS, sadly.<p>To get truly good easing functions, you usually have to write your own (the built-in ones in CSS are limited and rarely look good). Scrolling the page disables ALL transform repainting until the scroll has completed, so if you want to do anything fancy during a scroll you have to disable native scrolling and simulate it with scrollability (or something similar). iOS does not handle images well, especially high-res images (or many small images). Nor, sadly, does it handly opacity transforms well.<p>There are hacks to get around most of these limitations, but if you are, say, in a situation where you want to animate a series of images in a manner that involves opacity, you're going to get a royal headache. Think that's not that common? It happens more often than you'd think, usually in the form of fancy transitions between UI elements.