[css-ruby-1] Disallow collisions due to ruby overhang.

Author: fantasai

css-ruby-1/Overview.bs

@@ -1487,7 +1487,7 @@ Overhanging Ruby: the 'ruby-overhang' property</h3>
 	</dl>
 
 	When [=ruby annotations=] are not allowed to overhang,
-	the ruby behaves like a traditional inline box,
+	the [=ruby container=] behaves like a traditional inline box,
 	i.e. only its own contents are rendered within its boundaries
 	and adjacent elements do not cross the box boundary:
 
@@ -1497,13 +1497,15 @@ Overhanging Ruby: the 'ruby-overhang' property</h3>
 		<p class="caption">Simple ruby whose text is not allowed to overhang adjacent text
 	</div>
 
-	However, if a [=ruby annotation container=] is allowed
-	to overhang adjacent content
-	and it happens to be wider than its base,
-	then adjacent inline-level content
-	is partially rendered within the area of the [=ruby container box=],
-	allowing the [=ruby annotation=] to partially overlap
-	the upper/lower areas of such adjacent content:
+	However, if a [=ruby annotation container=] is allowed to overhang,
+	neighbouring content may overlap the [=ruby container box=],
+	allowing its [=ruby annotation=](s) to partially render over/under
+	surrounding inline-level content.
+	Overhang is only allowed to the extent
+	that it does not cause collisions between
+	the neighboring content
+	and the ruby container’s [=annotation boxes=]
+	or its overlapped [=base=]’s contents.
 
 	<div class="figure">
 		<img src="images/ro-a.gif"