Note that for some inputs (e.g. type="file") different UAs make them look totally different. And they might need to look different based on the input modality

Note that for some inputs (e.g. type="file") different UAs make them look totally different. And they might need to look different based on the input modality and so forth. We could specify a forced lowest-common-denominator behavior of some sort, but that seems like a disservice to users.