[css-ruby-1] Tweak diagram

Author: fantasai

css-ruby-1/Overview.bs

@@ -575,8 +575,8 @@ Unit Pairing and Spanning Annotations</h4>
 
 		<pre class=highlight>
 			<span class=column>|</span><span class=annot>[</span>  s p a n n i n g   a n n o t a t i o n <span class=annot>]</span><span class=column>|</span>
-			<span class=column>|</span><span class=annot>[</span> a1 <span class=annot>]</span><span class=column>|</span><span class=annot>[</span>ws<span class=annot>]</span><span class=column>|</span><span class=annot>[</span> a2 <span class=annot>]</span><span class=column>|</span> <span class=annot>[</span><span class=annot>]</span> <span class=column>|</span><span class=annot>[</span> a3 <span class=annot>]</span><span class=column>|</span><span class=annot>[</span>ws<span class=annot>]</span><span class=column>|</span><span class=annot>[</span> a4 <span class=annot>]</span><span class=column>|</span>
-			<span class=column>|</span><span class=base>[</span> b1 <span class=base>]</span><span class=column>|</span><span class=base>[</span>ws<span class=base>]</span><span class=column>|</span><span class=base>[</span> b2<span class=base>]</span><span class=base>]</span><span class=column>|</span><span class=base>[</span>ws<span class=base>]</span><span class=column>|</span><span class=base>[</span> b3 <span class=base>]</span><span class=column>|</span> <span class=base>[</span><span class=base>]</span> <span class=column>|</span><span class=base>[</span> b4 <span class=base>]</span><span class=column>|</span>
+			<span class=column>|</span><span class=annot>[</span> a1 <span class=annot>]</span><span class=column>|</span><span class=annot>[</span>ws<span class=annot>]</span><span class=column>|</span><span class=annot>[</span> a2 <span class=annot>]</span><span class=column>|</span><span class=annot>[</span>  <span class=annot>]</span><span class=column>|</span><span class=annot>[</span> a3 <span class=annot>]</span><span class=column>|</span><span class=annot>[</span>ws<span class=annot>]</span><span class=column>|</span><span class=annot>[</span> a4 <span class=annot>]</span><span class=column>|</span>
+			<span class=column>|</span><span class=base>[</span> b1 <span class=base>]</span><span class=column>|</span><span class=base>[</span>ws<span class=base>]</span><span class=column>|</span><span class=base>[</span> b2 <span class=base>]</span><span class=column>|</span><span class=base>[</span>ws<span class=base>]</span><span class=column>|</span><span class=base>[</span> b3 <span class=base>]</span><span class=column>|</span><span class=base>[</span>  <span class=base>]</span><span class=column>|</span><span class=base>[</span> b4 <span class=base>]</span><span class=column>|</span>
 		</pre>
 
 		Blue brackets (<tt class=base>[ ]</tt>) represent [=base boxes=],