CSS keywords serialize in lower case. https://drafts.csswg.org/cssom/#serializing-css-values "To serialize a CSS component value depends on the component, as follows: keyword The keyword converted to ASCII lowercase." A test page shows that 'sRGB' and 'linearRGB' are serialized in lower case in Firefox and Chrome Canary, but not Safari or Edge: https://jsfiddle.net/ericwilligers/0y4m7h9x/
This is also affecting the properties color-interpolation, color-rendering, image-rendering, shape-rendering, text-rendering with their keywords like geometricprecision, optimizelegibility, optimizequality, optimizespeed
<rdar://problem/96321532>
We still do not match Firefox or Chrome behavior here.