wording tweak

Author: fantasai

selectors4/Overview.html

@@ -1979,9 +1979,9 @@ <h3 id=active-pseudo><span class=secno>8.3. </span> The input focus
   <h2 id=time-pseudo><span class=secno>9. </span> Time-linear Presentation
    Pseudo-classes</h2>
 
-  <p>These pseudo-classes classify elements with respect to an active
-   position in a time-dimensional canvas, such as during speech rendering of
-   an HTML document.
+  <p>These pseudo-classes classify elements with respect to the
+   currently-displayed or active position in a time-dimensional canvas, such
+   as during speech rendering of an HTML document.
 
   <h3 id=current-pseudo><span class=secno>9.1. </span> The current-element
    pseudo-class <code>:current</code></h3>

selectors4/Overview.src.html

@@ -1461,8 +1461,8 @@ <h3 id="active-pseudo">
 <h2 id="time-pseudo">
 Time-linear Presentation Pseudo-classes</h2>
 
-  <p>These pseudo-classes classify elements with respect to an active
-    position in a time-dimensional canvas,
+  <p>These pseudo-classes classify elements with respect to the
+    currently-displayed or active position in a time-dimensional canvas,
     such as during speech rendering of an HTML document.
 
 <h3 id="current-pseudo">