Add a reference to default object size .

Author: tabatkins

css3-images/Overview.html

@@ -874,8 +874,10 @@ <h2 id=gradients><span class=secno>4. </span> Gradients</h2>
     class=property>background-size</code>&rsquo; is explicitly set to a value
     such as &lsquo;<code class=css>100px 200px</code>&rsquo;, then the <a
     href="#gradient-box"><i>gradient box</i></a> will be 100px wide and 200px
-    tall. Similarly, for a gradient used as a list-style-image, the box would
-    be a 1em square.</p>
+    tall. Similarly, for a gradient used as a &lsquo;<code
+    class=property>list-style-image</code>&rsquo;, the box would be a 1em
+    square, which is the <a href="#default-object-size"><i>default object
+    size</i></a> for that property.</p>
   </div>
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css3-images/Overview.src.html

@@ -484,7 +484,7 @@ <h2 id="gradients">
 	object size</i>, referred to as the <dfn>gradient box</dfn>.  However, the gradient itself has no <i>intrinsic dimensions</i>.</p>
 
 	<div class='example'>
-		<p>An image without intrinsic dimensions will always fill its painting area perfectly.  For example, if you use a gradient in 'background-image' with 'background-size' set to its default, the gradient will fill the element's padding box.  If 'background-size' is explicitly set to a value such as ''100px 200px'', then the <i>gradient box</i> will be 100px wide and 200px tall.  Similarly, for a gradient used as a list-style-image, the box would be a 1em square.</p>
+		<p>An image without intrinsic dimensions will always fill its painting area perfectly.  For example, if you use a gradient in 'background-image' with 'background-size' set to its default, the gradient will fill the element's padding box.  If 'background-size' is explicitly set to a value such as ''100px 200px'', then the <i>gradient box</i> will be 100px wide and 200px tall.  Similarly, for a gradient used as a 'list-style-image', the box would be a 1em square, which is the <i>default object size</i> for that property.</p>
 	</div>
 
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