[css-inline-3] Pull out painting comments from the sizing section.

Author: fantasai

css-inline-3/Overview.bs

@@ -236,6 +236,13 @@ Layout Within Line Boxes</h3>
 	[=margins=], [=padding=], [=borders=], and a 'line-height',
 	and thus influence these calculations just like boxes with content.
 
+<h3 id="paint-order">
+Painting Order</h3>
+
+	Except as specified for [=positioned boxes=] (see [[!CSS-POSITION-3]])
+	[=inline-level boxes=] are painted in [=document order=];
+	the 'z-index' property does not generally apply.
+
 <h2 id="css-metrics">
 Baselines and Alignment Metrics</h2>
 
@@ -828,15 +835,6 @@ Line Spacing: the 'line-height' property</h3>
 	for instance taking external leading metrics into account
 	only in the ''line-height/normal'' case.
 
-	Although margins, borders, and padding of non-replaced elements
-	do not enter into the line box calculation,
-	they are still rendered around inline boxes.
-	This means that if the height specified by 'line-height'
-	is less than the content height of contained boxes,
-	backgrounds and colors of padding and borders may "bleed" into adjoining line boxes.
-	User agents should render the boxes in document order.
-	This will cause the borders on subsequent lines
-	to paint over the borders and text of previous lines.
 
 	Note: CSS&nbsp;2 does not define what the content area of an inline box is
 	(see [[#line-fill]])
@@ -919,6 +917,15 @@ Line Sizing Containment: the 'line-sizing' property</h3>
 	In the latter case, an individual inline could say "pay attention to me"
 	or "don't pay attention to me".
 
+	Note: Although margins, borders, and padding of [=inline boxes=]
+	with ''line-sizing: legacy''
+	do not enter into the line box calculation,
+	they are still rendered around these boxes.
+	This means that if the size specified by 'line-height'
+	is less than the size of the box,
+	backgrounds and borders can “bleed” into adjoining line boxes,
+	potentially obscuring earlier content.
+
 <h3 id="leading-trim-property">
 Half-Leading Control</h3>