Don't use a bunch of hacky hacks to make sites work better on devices that you know. Use real world data of width, height and resolution to make it behave on all devices.
Why do web devs have such a problem with things like dpi and icon sizes? Its not that hard, but does require some trickery since DPI is not an ECMA standard.
Till there _is_ a standard way of getting DPI, Apple needs a button (it has to be a button or something even simpler, because it is for an Apple user) to emulate a standard DPI.