[css-ruby] Improve cross linking and clarify terminology

This reduces apparent ambiguities that were actually well defined,
but through non obvious terminology.

See #5047

css-ruby-1/Overview.bs

@@ -211,26 +211,28 @@ Ruby-specific 'display' Values</h3>
 <h4 id="formatting-context">
 The Ruby Formatting Context</h4>
 
-	[=Ruby containers=] are non-atomic inline-level boxes.
-	Like inline boxes, they break across lines,
-	and their containing block is the nearest block container ancestor.
-	And just as the contents of an inline box
-	participate in the same inline formatting context that contains the inline box itself,
+	[=Ruby containers=] are non-atomic [=inline-level=] boxes.
+	Like [=inline boxes=] (see [[css-inline-3#model]]),
+	they break across lines,
+	and their [=containing block=] is the nearest [=block container=] ancestor.
+	And just as the contents of an [=inline box=]
+	participate in the same [=inline formatting context=] that contains the [=inline box=] itself,
 	a [=ruby container=] and its base-level contents
-	participate in the same inline formatting context that contains the [=ruby container=] itself.
+	participate in the same [=inline formatting context=] that contains the [=ruby container=] itself.
 
 	However [=ruby containers=] also establish a <dfn export>ruby formatting context</dfn>
-	that builds further structure around their segment of the inline formatting context.
+	that builds further structure around their segment of the [=inline formatting context=].
+	<span class=note>Note: this [=formatting context=] is <em>not</em> an [=independent formatting context=].</span>
 	[=Ruby bases=], [=ruby annotations=], [=ruby base containers=], and [=ruby annotation containers=]
 	are <dfn export lt="internal ruby boxes|internal ruby display types">internal ruby boxes</dfn>:
 	like [=internal table elements=],
 	they have specific roles in ruby layout,
 	and participate in their [=ruby container=]’s [=ruby formatting context=].
 
-	As with the contents of inline boxes,
-	the containing block for the contents of a [=ruby container=] (and all its [=internal ruby boxes=])
-	is the containing block of the [=ruby container=].
-	So floats, for example, are trapped by the [=ruby container=]’s containing block,
+	As with the contents of [=inline boxes=],
+	the [=containing block=] for the contents of a [=ruby container=] (and all its [=internal ruby boxes=])
+	is the [=containing block=] of the [=ruby container=].
+	So floats, for example, are trapped by the [=ruby container=]’s [=containing block=],
 	not any of the ruby box types.
 
 	Issue: Are internal ruby boxes inline-level?