CSS: Clarify computed style, closes jquerygh-322

Author: dmethvin

entries/css.xml

@@ -15,10 +15,11 @@
         <desc>An array of one or more CSS properties.</desc>
       </argument>
     </signature>
-    <desc>Get the value of style properties for the first element in the set of matched elements.</desc>
+    <desc>Get the computed style properties for the first element in the set of matched elements.</desc>
     <longdesc>
       <p>The <code>.css()</code> method is a convenient way to get a style property from the first matched element, especially in light of the different ways browsers access most of those properties (the <code>getComputedStyle()</code> method in standards-based browsers versus the <code>currentStyle</code> and <code>runtimeStyle</code> properties in Internet Explorer) and the different terms browsers use for certain properties. For example, Internet Explorer's DOM implementation refers to the <code>float</code> property as <code>styleFloat</code>, while W3C standards-compliant browsers refer to it as <code>cssFloat</code>. For consistency, you can simply use <code>"float"</code>, and jQuery will translate it to the correct value for each browser.</p>
-      <p>Also, jQuery can equally interpret the CSS and DOM formatting of multiple-word properties. For example, jQuery understands and returns the correct value for both <code>.css( "background-color" )</code> and <code>.css( "backgroundColor" )</code>. Different browsers may return CSS color values that are logically but not textually equal, e.g., #FFF, #ffffff, and rgb(255,255,255).</p>
+      <p>Also, jQuery can equally interpret the CSS and DOM formatting of multiple-word properties. For example, jQuery understands and returns the correct value for both <code>.css( "background-color" )</code> and <code>.css( "backgroundColor" )</code>.</p>
+	  <p>Note that the <em>computed style</em> of an element may not be the same as the value specified for that element in a style sheet. For example, computed styles of dimensions are almost always pixels, but they can be specified as em, ex, px or % in a style sheet. Different browsers may return CSS color values that are logically but not textually equal, e.g., #FFF, #ffffff, and rgb(255,255,255).</p>
       <p>Retrieval of shorthand CSS properties (e.g., <code>margin</code>, <code>background</code>, <code>border</code>), although functional with some browsers, is not guaranteed. For example, if you want to retrieve the rendered <code>border-width</code>, use: <code>$( elem ).css( "borderTopWidth" )</code>, <code>$( elem ).css( "borderBottomWidth" )</code>, and so on.</p>
       <p><strong>As of jQuery 1.9</strong>, passing an array of style properties to <code>.css()</code> will result in an object of property-value pairs. For example, to retrieve all four rendered <code>border-width</code> values, you could use <code>$( elem ).css([ "borderTopWidth", "borderRightWidth", "borderBottomWidth", "borderLeftWidth" ])</code>. </p>
     </longdesc>