simplify normative text; elaborate note

Author: delan

css-pseudo-4/Overview.bs

@@ -989,22 +989,15 @@ Text and Text Decorations</h4>
     </div>
   </div>
 
-  While the element’s own
-  <a href="https://www.w3.org/TR/css-text-decor/#line-decoration">line decorations</a>
-  are propagated from
-  containing <a spec=css-text-decor>decorating boxes</a>
-  as usual,
-  decorations introduced by [=highlight pseudo-elements=]
-  apply only to the text
-  directly associated with the [=originating element=]
-  (or intervening [=pseudo-element=] such as ''::first-line'' or ''::first-letter'').
-
-  Note: Because highlight decorations
-  are propagated through inheritance,
-  not through the box tree,
-  they can be declared on the root element
-  and still reliably decorate out-of-flow descendants,
-  which is not the case for the element’s own decorations.
+  <a href="https://www.w3.org/TR/css-text-decor/#line-decoration">Line decorations</a> introduced by [=highlight pseudo-elements=]
+  apply only to the text associated with their [=originating element=],
+  and are not propagated to descendants
+  except via property [=inheritance=] (as described [[#highlight-cascade|above]]).
+
+  Note: Unlike the element’s own decorations,
+  decorations declared on the root element’s highlights
+  propagate to [=out-of-flow|out-of-flow elements=] and [=inline blocks=],
+  with thickness and position varying between descendants.
 
 <h4 id="highlight-replaced">
 Replaced Elements</h4>