[css-inline-3] Exclude auto from vertical-align shorthand. w3c#5235

Author: fantasai

css-inline-3/Overview.bs

@@ -664,7 +664,7 @@ Transverse Box Alignment: the 'vertical-align' property</h3>
 
 	<pre class="propdef shorthand">
 	Name: vertical-align
-	Value: <<'baseline-source'>> || <<'alignment-baseline'>> || <<'baseline-shift'>>
+	Value: [ first | last] || <<'alignment-baseline'>> || <<'baseline-shift'>>
 	Initial: baseline
 	Applies to: see individual properties
 	Inherited: no
@@ -678,7 +678,10 @@ Transverse Box Alignment: the 'vertical-align' property</h3>
 	and [=post-alignment shift=] ('baseline-shift')
 	in a single declaration.
 
-	Values are the same as for the corresponding longhand properties, see below.
+	If ''baseline-source/first'' or ''baseline-source/last'' is specified,
+	it sets 'baseline-source'
+	(which is otherwise reset to ''baseline-source/auto'').
+	Other values are as for the corresponding longhand properties, see below.
 
 	<p class="advisement">
 		Authors should use this shorthand ('vertical-align') instead of its longhands,