[css-text-3] Refactor wording slightly. #4781

Author: fantasai

css-text-3/Overview.bs

@@ -2547,11 +2547,12 @@ Line Breaking Details</h3>
       i.e. where it is “normal” and permissible to break lines of text.
       Specifically it controls whether a <a>soft wrap opportunity</a>
       generally exists
-      between adjacent <a>typographic letter units</a>
-      (and/or non-<a>letter</a> <a>typographic character units</a>
+      between adjacent <a>typographic letter units</a>,
+      treating non-<a>letter</a> <a>typographic character units</a>
       belonging to the
       <code>NU</code>, <code>AL</code>, <code>AI</code>, or <code>ID</code>
-      Unicode line breaking classes [[!UAX14]]).
+      Unicode line breaking classes [[!UAX14]]
+      as <a>typographic letter units</a> for this purpose (only).
       It does not affect rules governing the <a>soft wrap opportunities</a>
       created by [=white space=] (as well as by [=other space separators=]) and around punctuation.
       (See 'line-break' for controls affecting punctuation and small kana.)
@@ -2654,10 +2655,10 @@ Line Breaking Details</h3>
       <dd>Breaking is allowed within “words”:
         specifically,
         in addition to <a>soft wrap opportunities</a> allowed for ''word-break/normal'',
-        any <a>typographic character units</a> resolving to the
+        any <a>typographic letter units</a>
+        (and any <a>typographic character units</a> resolving to the
         <code>NU</code> (“numeric”), <code>AL</code> (“alphabetic”), or <code>SA</code> (“Southeast Asian”)
-        line breaking classes [[!UAX14]]
-        and all <a>typographic letter units</a> regardless of line breaking class
+        line breaking classes [[!UAX14]])
         are instead treated as <code>ID</code> (“ideographic characters”)
         for the purpose of line-breaking.
         Hyphenation is not applied.