likely reduction in properties to 2-3 per research

likely reduction in properties to 2-3 per research, link issue #1960 and research so far, encouragement for contributions

css-scrollbars-1/Overview.bs

@@ -63,7 +63,13 @@ Media: visual
 
 These properties allow the author to set colors for various aspects of a scrollbar.
 
-<dl dfn-type="value" dfn-for="scrollbar-3dlight-color">
+Note: Per <a href="https://github.com/w3c/csswg-drafts/issues/1960">Issue 1960</a>, 
+the list of scrollbar-*-color properties is likely to be reduced to 2-3 (ideally 2), 
+with current candidates being scrollbar-base-color, scrollbar-face-color, scrollbar-track-color, 
+per <a href="https://www.w3.org/wiki/Css-scrollbars#Use-cases">research so far</a>, 
+and preferably only two of those. Additional input, data, suggestions welcome at those links!
+
+<dl dfn-type="value" dfn-for="scrollbar-base-color">
 <dt><dfn>normal</dfn>
 <dd>default platform rendering for that portion of the scrollbar, in the absence of any other 
 related scrollbar color properties. See details below for which scrollbar color are related to which.