[css-box-4] Remove effect of margin-trim on floats. w3c#8547

Author: fantasai

css-box-4/Overview.bs

@@ -387,7 +387,7 @@ Margins at Container Edges: the 'margin-trim' property {#margin-trim}
 		<dt><dfn>inline-end</dfn>
 		<dt><dfn>block-end</dfn>
 		<dd>
-			For in-flow boxes and floats contained by this box,
+			For in-flow boxes contained by this box,
 			margins adjacent to the box’s specified edges
 			are truncated to zero.
 			It also truncates any descendant margins collapsed with such a margin
@@ -419,6 +419,10 @@ Margins at Container Edges: the 'margin-trim' property {#margin-trim}
 	if the box establishes a <a>fragmentation context</a>.
 	See also <a href="https://github.com/w3c/csswg-drafts/issues/3314">Issue 3314</a>.
 
+	Note: This property has no effect on the margins of floats
+	when specified on a [=block container=];
+	a future level of this module may introduce specific controls for floats.
+
 <h4 id="margin-trim-block">
 Trimming Block Container Content</h4>
 
@@ -434,6 +438,8 @@ Trimming Block Container Content</h4>
 
 	ISSUE(6922): Define effect on inlines (if any) and in inline axis (if any).
 
+<!--
+
 	It also affects floats
 	for which the [=block container=] is a [=containing block=] by:
 	<ul>
@@ -459,6 +465,8 @@ Trimming Block Container Content</h4>
 
 	ISSUE(3256): Floats definition needs more work.
 
+-->
+
 <h4 id="margin-trim-flex">
 Trimming Flex Container Content</h4>
 
@@ -595,6 +603,10 @@ Recent Changes {#changes}
 ==============
 
 	Changes since the previous Working Draft include:
+	* Removing the effect of 'margin-trim' on floats,
+		because there are use cases for both trimming and not trimming their margins,
+		and it is complicated to imlement.
+		(<a href="https://github.com/w3c/csswg-drafts/issues/8547">Issue 8547</a>)
 	* Clarifying that only descendant margins are trimmed by 'margin-trim'
 		even if self or sibling margins would have collapsed with the trimmed margin.