[css-anchor-1] Change physical side keywords used in the wrong axis to just make the query invalid, not the function. w3c#7487

Author: tabatkins

css-anchor-1/Overview.bs

@@ -97,11 +97,11 @@ The ''anchor()'' function has three arguments:
 	<dfn value for=anchor()>right</dfn>,
 	<dfn value for=anchor()>top</dfn>,
 	and <dfn value for=anchor()>bottom</dfn>)
-	must only be used in [=inset properties=]
-	corresponding to the same axis:
-	for example, ''top'' and ''bottom'' are valid in 'top' and 'bottom',
-	but not in 'left' and 'right'.
-	Using wrong-axis keywords makes the function invalid.
+	are only useful in [=inset properties=]
+	corresponding to their corresponding axis:
+	for example, using ''top'' and ''bottom'' in 'left' or 'right'
+	(or in 'inset-inline-start' if the inline axis is horizontal, etc)
+	results in an [=invalid anchor query=].
 
 	The logical <<anchor-side>> keywords
 	(<dfn value for=anchor()>start</dfn>,
@@ -348,6 +348,15 @@ Note: The Popup API, for example,
 defines an [=implicit anchor element=] for a popup--
 the element that the popup is attached to.
 
+<!--
+ ███████  ██     ██ ████████ ████████  ████ ████████  ██████ 
+██     ██ ██     ██ ██       ██     ██  ██  ██       ██    ██
+██     ██ ██     ██ ██       ██     ██  ██  ██       ██      
+██     ██ ██     ██ ██████   ████████   ██  ██████    ██████ 
+██  ██ ██ ██     ██ ██       ██   ██    ██  ██             ██
+██    ██  ██     ██ ██       ██    ██   ██  ██       ██    ██
+ █████ ██  ███████  ████████ ██     ██ ████ ████████  ██████ 
+-->
 
 Anchor Queries {#queries}
 --------------
@@ -363,6 +372,9 @@ only if all of the following conditions are true:
 * Their function is used on an element that is [=absolutely-positioned=].
 * If representing an ''anchor()'' function,
 	the function is being used in an [=inset property=].
+* If representing an ''anchor()'' function
+	and the <<anchor-side>> keyword is a physical keyword,
+	it's used in an [=inset property=] in the corresponding axis.
 * If representing an ''anchor-size()'' function,
 	the function is being used in a [=sizing property=].
 * There is a [=target anchor element=]