Shift the paragraphs about abspos flexbox items to their own section.

Author: tabatkins

css3-flexbox/Overview.src.html

@@ -187,6 +187,9 @@ <h3 id='flex-items'>
 		<p>Notice that block element "not-an-item6.3" is not a separate flexbox item, because it is contained inside an inline element which is being wrapped into an anonymous flex item.  Similarly, the block element "not-an-item1.5" is not a flexbox item, because it's absolutely positioned and thus out of flow.</p>
 	</div>
 
+<h4 id='abspos-flexbox-items'>
+Positioning Absolutely Positioned Flexbox Items</h4>
+
 	<p>Absolutely positioned children of a flexbox are not <i>flexbox items</i>, but their "static position" (their position when the 'top'/'right'/'bottom'/'left' properties are ''auto'') responds somewhat to the flexbox's various properties.  The element's static position in the flexbox's <i>cross axis</i> is on the <i>cross-start</i> edge of the flexbox's content box.  The static position in the flexbox's <i>main axis</i> is slightly more complex to compute:</p>
 
 	<p>First, find the element's <dfn>hypothetical neighbors</dfn> by assuming that the element is a normal <i>flexbox item</i> with ''flex-order:0'', and reorder the flexbox's contents as mandated by 'flex-order'.  The <i>flexbox items</i> immediately preceding and following the element in the flexbox's direction (if any) are the element's <i>hypothetical neighbors</i>.</p>