[css-sizing-3] Wording tweaks to clean up intro text after dropping stretch/fit-content.

Author: fantasai

css-sizing-3/Overview.bs

@@ -75,6 +75,7 @@ Terminology</h2>
 		<dt><dfn>inner size</dfn>
 		<dd>
 			The <a href="https://www.w3.org/TR/css2/box.html#box-dimensions">content-box</a> size of a <a>box</a>.
+
 		<dt><dfn>outer size</dfn>
 		<dd>
 			The <a href="https://www.w3.org/TR/css2/box.html#box-dimensions">margin-box</a> size of a <a>box</a>.
@@ -142,6 +143,9 @@ Terminology</h2>
 <h3 id='auto-box-sizes'>
 Auto Box Sizes</h3>
 
+	There are four types of automatically-determined sizes in CSS
+	(sizes resulting fromy ''width/auto'' sizing rules, depending on context):
+
 	<dl export>
 		: <dfn>stretch-fit size</dfn>
 		: <dfn>stretch-fit inline size</dfn>
@@ -261,9 +265,8 @@ New Keywords for 'width' and 'height'</h3>
 	New values: max-content | min-content
 	</pre>
 
-	<p>There are four types of automatically-determined sizes in CSS (which
-		are represented in the width and height properties by the keywords
-		defined above):
+	<p>These new values allow authors to explicitly request that a box
+	take its intrinsic size:
 
 	<dl dfn-type=value dfn-for="width, min-width, max-width, height, min-height, max-height">
 <!--
@@ -399,7 +402,7 @@ Column Sizing Keywords</h3>
 			<code>min(<a>max-content size</a>, max(<a>min-content size</a>, <<length-percentage>>))</code>
 	</dl>
 
-	Note: The column width does not vary by column.
+	Note: The column width never varies by column.
 	When the column width is informed by the multi-column element's contents
 	(as in the keywords above),
 	all of its contents are taken under consideration