CSS Filters: inline inputs need labels

[dstorey]

https://developer.microsoft.com/en-us/microsoft-edge/testdrive/demos/css3filters/

They're currently label-less. The text around them are CODE elements. Need to think about how to fix this as there is text either side of the input. It should probably be something like aria-label="greyscale value" or something. Probably also want to reflect that it is a percentage value.