Clarify wording, as discussed in http://lists.w3.org/Archives/Public/www-archive/2012Feb/0018.html .

Author: dbaron

css3-animations/Overview.html

@@ -376,7 +376,7 @@ <h2 id=keyframes><span class=secno>3. </span>Keyframes</h2>
    invalid, the animation of that property proceeds as if that keyframe did
    not exist. Conceptually, it is as if a set of keyframes is constructed for
    each property that is present in any of the keyframes, and an animation is
-   run independently for each one.
+   run independently for each property.
 
   <div class=example>
    <p style="display:none"> Example(s):</p>

css3-animations/Overview.src.html

@@ -240,7 +240,7 @@ <h2>Keyframes</h2>
       <p>
         If property is not specified for a keyframe, or is specified but invalid, the animation of that property proceeds
         as if that keyframe did not exist. Conceptually, it is as if a set of keyframes is constructed for each property
-        that is present in any of the keyframes, and an animation is run independently for each one.
+        that is present in any of the keyframes, and an animation is run independently for each property.
       </p>
       <div class="example">
         <p style="display:none">