[css-timing] Mark steps and step-position as definitions

Author: birtles

css-timing/Overview.bs

@@ -221,7 +221,7 @@ Some example step timing functions are illustrated below.
 </figure>
 
 A [=step timing function=] is defined by a non-zero positive number of
-<var>steps</var>, and a <var>step position</var> property that may be either
+<dfn>steps</dfn>, and a <dfn>step position</dfn> property that may be either
 <a value for="steps()">start</a> or <a value for="steps()">end</a>.
 
 At the exact point where a step occurs the result of the function is
@@ -234,31 +234,31 @@ The [=output progress value=] is calculated from the [=input progress value=]
 and [=before flag=] as follows:
 
 1.   Calculate the <var>current step</var> as <code>floor([=input progress
-     value=] &times; <var>steps</var>)</code> clamped to the range [0,
-     <var>steps</var>].
+     value=] &times; [=steps=])</code> clamped to the range [0,
+     [=steps=]].
 
-1.   If the <var>step position</var> property is <a value
-     for="steps()">start</a> and <var>current step</var> &lt; <var>steps</var>,
-     increment <var>current step</var> by one.
+1.   If the [=step position=] property is <a value for="steps()">start</a> and
+     <var>current step</var> &lt; [=steps=], increment <var>current
+     step</var> by one.
 
 1.   If <em>all</em> of the following conditions are true:
 
      *   the [=before flag=] is set,
      *   <var>current step</var> &gt; 0, <em>and</em>
-     *   [=input progress value=] &times; <var>steps</var> mod 1 equals zero
-         (that is, if [=input progress value=] &times; <var>steps</var> is
+     *   [=input progress value=] &times; [=steps=] mod 1 equals zero
+         (that is, if [=input progress value=] &times; [=steps=] is
          integral), then
 
      decrement <var>current step</var> by one.
 
 1.   The [=output progress value=] is <code><var>current step</var>
-     / <var>steps</var></code>.
+     / [=steps=]</code>.
 
 <div class=example>
 
 As an example of how the [=before flag=] affects the behavior of this function,
-consider an animation with a [=step timing function=] whose <var>step
-position</var> is <a value for="steps()">start</a> and which has a positive
+consider an animation with a [=step timing function=] whose [=step
+position=] is <a value for="steps()">start</a> and which has a positive
 delay and backwards fill.
 
 For example, using CSS animation:
@@ -299,7 +299,7 @@ The meaning of each value is as follows:
     It must be a positive integer greater than 0.
     The second parameter, which is optional, is
     either the value <dfn value for="steps()">start</dfn> or <dfn value
-    for="steps()">end</dfn>, and specifies the <var>step position</var>.
+    for="steps()">end</dfn>, and specifies the [=step position=].
     If the second parameter is omitted, it is given the value ''end''.
 
 </dl>
@@ -329,7 +329,7 @@ defined in [[CSSOM]] with the following additional requirements:
     ''steps()'' function or either of the ''step-start'' or ''step-end''
     keywords, are serialized as follows:
 
-    1.   If the <var>step position</var> is ''end'', serialize
+    1.   If the [=step position=] is ''end'', serialize
          as <a lt="steps()" function>steps(&lt;integer&gt;)</a>.
 
     2.   Otherwise, serialize as <a lt="steps()"