[css-sizing-4] Add min-width:auto aspect ratio example from #4637

Author: fantasai

css-sizing-4/Overview.bs

@@ -412,7 +412,24 @@ Automatic Content-based Minimum Sizes</h4>
 		</pre>
 	</div>
 
+	<div class="example">
+		This automatic minimum operates in both axes.
+		Consider this example:
+		<pre>
+			&lt;div style="height: 100px; aspect-ratio: 1/1;">
+				&lt;span style="display: inline-block; width: 50px;">&lt;/span>
+				&lt;span style="display: inline-block; width: 150px;">&lt;/span>
+			&lt;/div>
+		</pre>
 
+		The 'width' of the container, being ''width/auto'',
+		resolves through the aspect ratio to 100px.
+		However, its 'min-width', being ''min-width/auto'',
+		resolves to 150px.
+		The resulting width of the container is thus 150px.
+		To ignore the contents when sizing the container,
+		''min-width: 0'' can be specified.
+	</div>
 
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