[css-text] Tweak wording to better allow river-avoidance

Author: fantasai

css-text/Overview.html

@@ -2199,11 +2199,12 @@ <h3 id=text-justify><span class=secno>7.3. </span> Justification Method:
    href="#expansion-opportunity"><i>Expansion opportunities</i></a> are
    divided into different priority levels: within a level, all <a
    href="#expansion-opportunity"><i>expansion opportunities</i></a> are
-   expanded or compressed by the same amount, in proportion to the <a
-   href="#expansion-opportunity"><i>expansion opportunity</i></a>’s
-   ‘<code class=property>font-size</code>’. In the case of an <a
-   href="#expansion-opportunity"><i>expansion opportunity</i></a> introduced
-   by a single <a href="#character"><i>character</i></a>, (as with ‘<a
+   expanded or compressed at the same priority, with space distributed in
+   proportion to the <a href="#expansion-opportunity"><i>expansion
+   opportunity</i></a>’s ‘<code class=property>font-size</code>’. In
+   the case of an <a href="#expansion-opportunity"><i>expansion
+   opportunity</i></a> introduced by a single <a
+   href="#character"><i>character</i></a>, (as with ‘<a
    href="#word-spacing0"><code class=property>word-spacing</code></a>’) the
    ‘<code class=property>font-size</code>’ of that <a
    href="#character"><i>character</i></a> is used; in the case of an <a

css-text/Overview.src.html

@@ -1640,8 +1640,8 @@ <h3 id="text-justify">
       as points where the justification algorithm may alter spacing within the text.
       <i>Expansion opportunities</i> are divided into different priority levels:
       within a level, all <i>expansion opportunities</i> are
-      expanded or compressed by the same amount,
-      in proportion to the <i>expansion opportunity</i>’s 'font-size'.
+      expanded or compressed at the same priority,
+      with space distributed in proportion to the <i>expansion opportunity</i>’s 'font-size'.
       In the case of an <i>expansion opportunity</i> introduced by a single <i>character</i>,
       (as with 'word-spacing') the 'font-size' of that <i>character</i> is used;
       in the case of an <i>expansion opportunity</i> between <i>characters</i>,