[css-color-5] Lab default with LCH override

Author: svgeesus

css-color-5/Overview.bs

@@ -747,7 +747,7 @@ When an origin color is present, the following keywords can also be used in this
 Interpolation {#interpolation}
 ===================================
 
-In general, interpolation between <<color>> values of the same color space occurs by linearly interpolating each component separately.
+In general, interpolation between <<color>> values of the same color space occurs by linearly interpolating each component of the computed value of the color separately, in that colorspace.
 
 Issue: Should gamut mapping occur before or after interpolation?
 
@@ -756,8 +756,9 @@ Issue(4928): How to handle achromatic interpolation?
 Color space for interpolation {#interpolation-space}
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-If colors are not in the same color space, they are first converted to LCH and and interpolated as LCH colors.
+If colors are not in the same color space, they are first converted to Lab and and interpolated as Lab colors.
 Host syntax can override the interpolation color space and specify which color space is used for interpolation.
+For example, 'color-mix' and 'color-adjust' override the default to LCH.
 
 Issue: Should the colors at 0% and 100% be serialized with their original color spaces or converted to the interpolation space?