[css-color-adjust-1] No fallback colors, fix w3c#7007

Author: svgeesus

css-color-adjust-1/Overview.bs

@@ -504,11 +504,7 @@ Properties Affected by Forced Colors Mode {#forced-colors-properties}
 	if its [=computed value=] is a color other than a [=system color=],
 	its [=used value=] is instead forced to a [=system color=] as follows:
 
-	* If the color value indicates a “fallback” color
-		(as in the ''color()'' function in [[CSS-COLOR-5]])
-		and that fallback color is a [=system color=],
-		then the color is forced to that [=system color=].
-	* Else for 'background-color' in particular,
+	* For 'background-color' in particular,
 		it is forced to
 		the color opposite the 'color' property’s [=system color=] value
 		in the [=system color pairings=],