Re: input element - absolute positioning - determing width with left and right

> Is there some reason this has been left out of the CSS spec?  It  
> seems obvious to me that authors would want to apply CSS positioning  
> rules to all types of form elements.

Because many browsers use native controls, and, in fact, it is good
practice to maintain the native user interface, so as not to confuse
users of the platform, and the best way of accurately modelling the
native interface is to use native controls.

However, native controls do not necessarily fit the CSS model.

CSS, in principle, only hints at what to do and browsers are allowed
to ignore those hints if there are good reasons for doing so (which
may include commercial decisions).