Created attachment 468596 [details] repro video In STP and Safari 17.2 beta, I see that the position of lightness slider is not live updated when dragging, even though the color does live update. Reproduces with examples on https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input/color; video of what happens is attached.
<rdar://problem/118424469>
Moving to a different component, as WebKit does not control the UI here.