[css-position-3] Clarify alignment mapping for abspos insets. w3c#6607

Author: tabatkins

css-position-3/Overview.bs

@@ -718,9 +718,7 @@ Absolute (and Fixed) Positioning</h3>
 	If only one [=inset property=] in a given axis is ''top/auto'',
 	it is set to zero.
 	If both [=inset properties=] in a given axis are ''top/auto'', then,
-	depending on the box’s [=self-alignment property=] in the relevant axis
-	(treating ''align-self/normal'' as ''align-self/start''
-	and any [=distributed alignment|distributed=], [=baseline alignment|baseline=], or ''align-self/stretch'' alignment value as its fallback alignment):
+	depending on the box’s [=self-alignment property=] in the relevant axis:
 
 	<dl class=switch>
 		<dt>for ''align-self/self-start'' alignment or its equivalent
@@ -751,6 +749,12 @@ Absolute (and Fixed) Positioning</h3>
 			(<var>containing block size</var> - 2 &times; |<var>end distance</var>|).
 	</dl>
 
+	For the rules above,
+	ignore [=overflow alignment=],
+	and treat ''align-self/normal'' as ''align-self/start''
+	and any [=baseline alignment|baseline=] or ''align-self/stretch'' alignment value
+	as its fallback alignment.
+
 	If these adjustments result in
 	an effective [=containing block=] size in any axis less than zero,
 	then the [=weaker inset=] in the affected axis