[css-inline-3] non-zero borders/padding blocks leading-trim. #5237

Author: fantasai

css-inline-3/Overview.bs

@@ -1300,7 +1300,7 @@ Half-Leading Control: the 'leading-trim' property
 	On [=block containers=],
 	specifies whether to trim [=half-leading=]
 	at the start/end of its content
-	to the corresponding 'text-edge' metric of its [=root inline box=]
+	to the corresponding 'text-edge' metric
 	to better match the box’s [=content edge=] to its text content.
 
 	This property has no effect when 'text-edge' is ''text-edge/leading''.
@@ -1324,7 +1324,9 @@ Half-Leading Control: the 'leading-trim' property
 			For [=block containers=]:
 			trim the [=block-start=] side of the first formatted line
 			to the corresponding 'text-edge' metric of its [=root inline box=].
-			(If there is no such line, there is no effect.)
+			If there is no such line,
+			or if there is intervening non-zero padding or borders,
+			there is no effect.
 
 			For [=inline boxes=]:
 			trims the [=block-end=] side of the box
@@ -1336,7 +1338,9 @@ Half-Leading Control: the 'leading-trim' property
 			For [=block containers=]:
 			trim the [=block-end=] side of the last formatted line
 			to the corresponding 'text-edge' metric of its [=root inline box=].
-			(If there is no such line, there is no effect.)
+			If there is no such line,
+			or if there is intervening non-zero padding or borders,
+			there is no effect.
 
 			For [=inline boxes=]:
 			trims the [=block-end=] side of the box
@@ -2916,6 +2920,9 @@ Changes
 		to handle common practices for certain Indic scripts.
 		See Indic Layout Requirements.
 		(Issue 864)
+
+		Make non-zero padding and border block effects of 'leading-trim' from ancestors.
+		(Issue 5237)
 	
 
 	Changes since the