code: function(prop, callback) {
          // shortcut getComputedStyle function
          var s = function(el, p) {
              // this *can* be written to be smaller - see below, but in fact it doesn't compress in gzip as well, the commented
              // out version actually *adds* 2 bytes.
              // return document.defaultView.getComputedStyle(el, "").getPropertyValue(p.replace(/([A-Z])/g, "-$1").toLowerCase());
              return document.defaultView.getComputedStyle(el, "").getPropertyValue(cssstyle(p));
          }
          if (callback === undefined) {
          	var styles = [];
            this.each(function(el) {styles.push(s(el, prop))});
            return styles;
          } else return this.each(function(el) { callback(s(el, prop)); });
      }
docs: getStyle
  --------
  
  Returns the value of a single CSS property. Can also invoke a callback to perform more specific processing tasks related to the property value.
  Please note that the return type is always an Array of strings. Each string corresponds to the CSS property value for the element with the same index in the xui collection.
  
  ### syntax ###
  
  x$( selector ).getStyle( property, callback );
  
  ### arguments ###
  
  - property `String` is the name of the CSS property to get.
  - callback `Function` is called on each element in the collection and passed the property _(optional)_.
  
  ### example ###
  <ul id="nav">
  <li class="trunk" style="font-size:12px;background-color:blue;">hi</li>
  <li style="font-size:14px;">there</li>
  </ul>
  
  x$('ul#nav li.trunk').getStyle('font-size'); // returns ['12px']
  x$('ul#nav li.trunk').getStyle('fontSize'); // returns ['12px']
  x$('ul#nav li').getStyle('font-size'); // returns ['12px', '14px']
  
  x$('ul#nav li.trunk').getStyle('backgroundColor', function(prop) {
  alert(prop); // alerts 'blue'
  });