[css-lists] Rough draft rewrite of the ::marker intro section.

Author: tabatkins

css-lists-3/Overview.bs

@@ -88,25 +88,25 @@ Declaring a List Item</h2>
 <h2 id='markers'>
 Markers</h2>
 
-	The defining feature of a <a>list item</a> is its <dfn export>marker</dfn>,
+	The defining feature of the <a>list item</a> <a>display type</a> is its <i>marker</i>,
 	a symbol or ordinal that helps denote the beginning of each <a>list item</a> in a list.
+	List item boxes thus generate, in addition to their principal box,
+	a <dfn export lt="marker | marker box">marker box</dfn>
+	(represented by the ''::marker'' pseudo-element)
+	which contains and displays this marker.
 
 <h3 id='marker-pseudo'>
 The ''::marker'' Pseudo-Element</h3>
 
-	The ''::marker'' pseudo-element is automatically generated by a <a>list item</a>,
-	and is automatically filled with content
-	according to the <a>list item’s</a> 'list-style' property
-	(or its subproperties).
-
-	The ''::marker'' pseudo-element is generated as the first child of the <a>list item</a>,
+	The <a>marker box</a> generated by the ''::marker'' pseudo-element of a <a>list item</a>
+	is generated as the first child of the <a>list item</a>,
 	before the ''::before'' pseudo-element
-	(if that exists on the element).
-	''::marker''s are <a>inline</a> by default,
-	tho 'list-style-position' can cause them become <a>absolutely positioned</a>.
+	(if it exists on the element)
+	and filled with content
+	as defined in [[#content-property]].
 
-	The ''::marker'' pseudo-element only exists on <a>list items</a>.
-	On any other element,
+	<a>Marker boxes</a> only exist on <a>list items</a>;
+	on any other element,
 	the ''::marker'' pseudo-element's 'content' property must compute to ''content/none'',
 	which suppresses its creation.