[css-lists-3] Use subheadings instead of divs.

Author: fantasai

css-lists-3/Overview.bs

@@ -28,24 +28,6 @@ spec:infra; type:dfn;
 	text:string
 </pre>
 
-<style>
-/* Put nice boxes around each algorithm. */
-[data-algorithm]:not(.heading) {
-  padding: .5em;
-  border: thin solid #ddd; border-radius: .5em;
-  margin: .5em calc(-0.5em - 1px);
-}
-[data-algorithm]:not(.heading) > :first-child {
-  margin-top: 0;
-}
-[data-algorithm]:not(.heading) > :last-child {
-  margin-bottom: 0;
-}
-[data-algorithm] [data-algorithm] {
-    margin: 1em 0;
-}
-</style>
-
 <h2 id='intro'>
 Introduction</h2>
 
@@ -917,6 +899,9 @@ Creating and Inheriting Counters</h3>
 	The latest [=counter=] of a given name in that set
 	represents the “innermost” counter of that name.
 
+<h4 id="inheriting-counters">
+Inheriting Counters</h4>
+
 	<div algorithm>
 		An element [=inherit counters|inherits=] its initial set of counters
 		from its preceding <em>sibling</em>,
@@ -1006,14 +991,17 @@ Creating and Inheriting Counters</h3>
 	#counter-inheritance-example b.baz { color: blue; }
 	</style>
 
+<h4 id="instantiating-counters">
+Instantiating Counters</h4>
+
 	<div algorithm>
 		[=Counters=] are [=instantiated=] when named in 'counter-reset',
 		and also when not otherwise present if named in
 		'counter-increment', 'counter-set', or the ''counter()'' or ''counters()'' notations.
 		(Newly [=instantiated=] [=counters=] replace identically-named [=counters=] originating from previous siblings,
 		but are added in addition to identically-named [=counters=] originating from ancestor elements,
 		see [[#nested-counters]].)
-		To <dfn local-lt="instantiate">instantiate a counter</dfn>
+		To <dfn lt="instantiate counter" local-lt="instantiate">instantiate a counter</dfn>
 		of a given |name|
 		on an |element|
 		with a starting |value|: