[css-sizing-4] More w3c#6308 - discussion with chrishtr concluded that an on-screen c-v:hidden element using a phantom size would also still be bad.

Author: tabatkins

css-sizing-4/Overview.bs

@@ -553,10 +553,15 @@ Overriding Contained Intrinsic Sizes: the 'contain-intrinsic-*' properties</h3>
 
 		: <dfn>auto <<length>></dfn>
 		:: If the element has a [=last remembered size=],
-			and is currently [=skipping its contents=],
+			is currently [=skipping its contents=],
+			and is not [=relevant to the user=],
 			its [=explicit intrinsic inner size=]
 			is the [=last remembered size=].
 
+			Note: This occurs, for example,
+			when an element with ''content-visibility: auto''
+			is off-screen.
+
 			Otherwise,
 			its [=explicit intrinsic inner size=]
 			is the specified <<length>>.