[css-color-5] How exactly does the hue adjuster in color-adjust() work?

[tabatkins]

In 'color-adjust()`, the spaces with hue have a hue-adjuster that looks like (grammar folded together):

hue [shorter | longer | increasing | decreasing | specified ]? ?

This seems odd in at least two ways.

1. Adjusting a hue by percentage seems like it's a domain error. Hue is a circular range; it doesn't have a meaningful zero to adjust toward or away from. In HSL, blue hue 50% changes the hue from 240deg to 120deg, but green hue 50% adjusts it from 120deg to 60deg; I don't think there's a meaningful sense in which green is "half" of blue, or yellow is "half" of green.

2. The shorter/longer/etc keyword seems to not do anything? That keyword is for choosing between several behaviors of interpolating between two hues; that doesn't appear to be relevant here. The spec just refers to the definition of the keywords, but doesn't explain what they actually do, or have an example of it.

[svgeesus]

Closed by WG resolution to drop color-adjust()