[css-lists-3] Actually define the sizing of marker images.

Author: tabatkins

css-lists-3/Overview.bs

@@ -282,7 +282,7 @@ Generating Marker Contents</h3>
 
 		<dt>'list-style-image' on the [=originating element=] defines a [=marker image=]
 		<dd>
-			The '<a>marker box</a> contains
+			The <a>marker box</a> contains
 			an <a>anonymous</a> <a>inline</a> <a>replaced element</a>
 			representing the specified [=marker image=],
 			followed by a <a>text run</a> consisting of a single space (U+0020 SPACE).
@@ -343,6 +343,12 @@ Image Markers: the 'list-style-image' property</h3>
 			The element has no <a>marker image</a>.
 	</dl>
 
+	The [=marker image=] is sized
+	using the [=default sizing algorithm=]
+	[[css-images-3]]
+	with no [=specified size=]
+	and a [=default object size=] of 1em square.
+
 	<div class="example">
 		The following example sets the marker at the beginning of each list item to
 		be the image "ellipse.png".