Add a reference to CSS3-VALUES and simplify the value section accordingly

Author: Florian Rivoal

css4-mediaqueries/Overview.src.html

@@ -940,48 +940,26 @@ <h3 id="script">script</h3>
 
 <h2 id="values">Values</h2>
 
-<p>This specification also introduces two new values.</p>
+<p>Value types not defined in this specification, such as &lt;integer&gt;,
+&lt;number&gt; or &lt;resolution&gt;, are defined in [[!CSS3VAL]].  Other CSS
+modules may expand the definitions of these value types.</p>
 
-<p>The &lt;ratio> value is a positive (not zero or negative) &lt;integer>
-followed by optional whitespace, followed by a solidus ('/'), followed by
-optional whitespace, followed by a positive &lt;integer>.</p>
-
-<p>The &lt;resolution> value is a positive &lt;number> immediately followed
-by a unit identifier (''dpi'' or ''dpcm'').</p>
-
-<p>Whitespace, &lt;integer>, &lt;number> and other values used by this
-specification are the same as in other parts of CSS, normatively defined by
-CSS 2.1. [[!CSS21]]</p>
+<p>This specification also introduces one new value type.</p>
 
+<p>The &lt;ratio&gt; value type is a positive (not zero or negative)
+&lt;integer&gt; followed by optional whitespace, followed by a solidus ('/'),
+followed by optional whitespace, followed by a positive &lt;integer&gt;.</p>
 
 <h2 id="units">Units</h2>
 
-<p>The units used in media queries are the same as in other parts of
-CSS. For example, the pixel unit represents CSS pixels and not
-physical pixels.</p>
+<p>The units used in media queries are the same as in other parts of CSS, as
+defined in [[!CSS3VAL]]. For example, the pixel unit represents CSS pixels and
+not physical pixels.</p>
 
 <p>Relative units in media queries are based on the initial value, which means
 that units are never based on results of declarations. For example, in HTML,
 the ''em'' unit is relative to the initial value of 'font-size'.</p>
 
-<h3>Resolution</h3>
-
-<p>The ''dpi'' and ''dpcm'' units describe the resolution of an output
-device, i.e., the density of device pixels. Resolution unit identifiers
-are:</p>
-
-<dl>
-<dt>dpi</dt>
-<dd>dots per CSS ''inch''</dd>
-
-<dt>dpcm</dt>
-<dd>dots per CSS ''centimeter''</dd>
-</dl>
-
-<p>In this specification, these units are only used in the
-''resolution'' media feature.</p>
-
-
 <h2 id="changes">Changes</h2>
 <h3 id="changes-2012">Changes Since the Media Queries Level 3</h3>
 <p>The following changes were made to this specification since the