I am currently working on a web based administration interface which has a lot of controls, such as sliders, check boxes, input fields, etcetera. The interface should work on desktops, tablets and mobile phones. It is important that the controls are kept at a reasonable size across all platforms so that they remain useful on all sorts of screens and when using different input methods.
The working hypothesis is to use some flavour of responsive design, based on CSS media queries floated elements and relative units for the layout. The problem arises when determining the size of the control elements and font sizes.
The vast number of different pixel densities and physical sizes of the screens makes this an interesting problem. As if it was not hard enough knowing what way to choose, some vendors are experimenting with the good ol' pixel measurement (px) and adopting new interpretations of it to be able to display current websites in some kind of readable way.
Given the current and future development of screens, devices, input methods and so fourth, how would one go about to tackle this problem? Is there a way to adjust font sizes for instance so that they seem to be of similar sizes across all mobile devices? Is this the way to go or is there any best practices to consider when dealing with this kind of questions?