[css-inline-3] Application of text-box-trim to other FCs w3c#11038

Author: fantasai

css-inline-3/Overview.bs

@@ -1456,6 +1456,10 @@ Trimming Over/Under Text: the 'text-box-trim' property</h3>
 			simultaneously.
 	</dl>
 
+	Note: Like ''::first-line'',
+	this property does not apply to, or propagate through,
+	flex, grid, or table [=formatting contexts=].
+
 	Note: The [=block-end=] side does not coincide with the [=line-under=] side
 	when 'writing-mode' is ''vertical-lr''.
 
@@ -1467,6 +1471,13 @@ Trimming Over/Under Text: the 'text-box-trim' property</h3>
 	due to non-initial values of 'text-box-trim'
 	is handled the same as content that would overflow the box or line box otherwise.
 
+	Unlike ''::first-line'',
+	when applying to the first (or last) formatted line of a [=multi-column container=],
+	this property applies to the first (or last) formatted lines
+	of <em>every</em> column in the [=multi-column container=].
+
+	ISSUE(11363): What happens if the column is split by a spanner?
+
 <h3 id="text-box-edge">
 Text Trimming Metrics: the 'text-box-edge' property</h3>
 
@@ -3053,8 +3064,10 @@ Changes</h2>
 
 	Changes since the <a href="https://www.w3.org/TR/2024/WD-css-inline-3-20240812/">12 August 2024 Working Draft</a>:
 	<ul>
-		<li>Defined behavior of 'text-box-trim' on [=multi-column containers=].
-			(<a href="https://github.com/w3c/csswg-drafts/issues/5335">Issue 5335</a>)
+		<li>Defined behavior of 'text-box-trim' on [=multi-column containers=],
+			and clarified its application to (and through) other formatting contexts.
+			(<a href="https://github.com/w3c/csswg-drafts/issues/5335">Issue 5335</a>,
+			 <a href="https://github.com/w3c/csswg-drafts/issues/11038">Issue 11038</a>)
 	</ul>
 
 	Changes since the