[css-box-4] Clarify margin-trim does not affect inline-level margins nor inline-axis margins of block-level boxes w3c#6922

Author: fantasai

css-box-4/Overview.bs

@@ -453,8 +453,8 @@ Trimming Block Container Content</h4>
 		<li>Any margin collapsed with these margins.
 	</ul>
 
-	ISSUE(6922): Define effect on inlines (if any) and in inline axis (if any).
-
+	It has no effect on the [=inline-axis=] margins of [=block-level=] descendants,
+	nor on any margins of [=inline-level=] descendants.
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 	It also affects floats