[css-pseudo-4] Spaces are Zs not S ... #5830

Author: fantasai

css-pseudo-4/Overview.bs

@@ -331,12 +331,15 @@ First-Letter Text: ''::first-letter'' pseudo-element and its ''::prefix'' and ''
   </ul>
 
   <div class="note">
-    Informally represented, the first-letter text’s pattern here is
+    Informally represented, the [=first-letter text=]’s pattern here
+    can be roughly
+    (ignoring the exclusion of word separators from <code>Zs</code>)
+    represented as
     <code highlight="bnf" style="font-family: inherit">
-    (S|P)* (L|N)+ (S|P^(Ps|Pd))*</code>
+    (Zs|P)* (L|N)+ (Zs|P^(Ps|Pd))*</code>
     or, alternatively,
     <code highlight="bnf" style="font-family: inherit">
-    [S P]* [L N]+ [[S] [P--[Ps Pd]]]*</code>
+    [Zs P]* [L N]+ [[Zs] [P--[Ps Pd]]]*</code>
     <!-- this is not actually BNF, but it highlights better that way -->
   </div>